Data as of Aug 25, 2026 · Based on 319 AI responses from ChatGPT Search and Google AI Mode · See how Parse measures this
The ideal equipment depends on your event scale. Choose a Bosch Integrus system with an ISO-compliant booth for large-scale professional conferences. For freelance work and smaller events requiring portability and scalability, consider systems like the
Enersound 20-Person kit or
Enersound IC-12 console. -type kits offer a budget-friendly entry point, while the TT117 headset provides noise-isolating focus for individual work.
Brands AI recommends here
Named in 44% of answers
Named in 34% of answers
Provides portable and scalable solutions like the 20-person kit and the IC-12 console, ideal for freelance interpreters who need reliable, solid audio control that can adapt to smaller or temporary event spaces.
Named in 30% of answers
Named in 30% of answers
If you're a **freelance conference interpreter**, I'd build your kit around one principle: **your personal equipment should make you independent of the venue's setup, but you shouldn't try to replace a professional conference-interpreting system unless the client specifically needs you to provide one.** ## My…
If you're a freelance conference interpreter, I'd build your kit around one principle: your personal equipment should make you independent of the venue's setup, but you shouldn't try to replace a professional conference-interpreting system unless the client specifically needs you to provide one.
For simultaneous work, I'd favor a wired, closed or semi-closed headset with a good boom microphone rather than ordinary Bluetooth headphones. You want excellent speech isolation, a stable connection, and a microphone that stays in exactly the right position.
Good options include:
For example, the
is a sensible budget-conscious professional option.
I'd actually buy two headsets: your primary headset and a backup.
If you're interpreting remotely or the conference is feeding you audio from a laptop, a small USB audio interface is extremely useful. Look for:
This is much safer professionally than depending entirely on a laptop's built-in audio.
For hybrid conferences, I'd want a reasonably powerful laptop with:
I'd also carry a USB Ethernet adapter and a long Ethernet cable. Wi-Fi is one of the things I would least want to trust during a paid simultaneous assignment.
If the client expects you to supply the audience's listening equipment, you're entering a different category.
Portable systems such as the Williams AV Digi-Wave or Listen Technologies ListenTALK can transmit interpretation to audience receivers. For example:
And the
is an actual interpreter console designed for integration with FM, IR and Digi-Wave systems.
For a normal conference, though, I wouldn't buy one of these until you have clients who will pay for the additional equipment/service. They're a substantial investment, and professional conference venues often already have the infrastructure.
This is boring equipment until something fails—and then it's the most valuable stuff in your bag.
I'd carry:
If you're starting from scratch, I'd spend the money in this order:
| Priority | Equipment | Approx. importance |
|---|---|---|
| 1 | Professional wired headset | ⭐⭐⭐⭐⭐ |
| 2 | Reliable laptop | ⭐⭐⭐⭐⭐ |
| 3 | USB audio interface | ⭐⭐⭐⭐ |
| 4 | Ethernet adapter + cable | ⭐⭐⭐⭐ |
| 5 | Backup headset | ⭐⭐⭐⭐ |
| 6 | Power bank/backup power | ⭐⭐⭐⭐ |
| 7 | USB hub/adapters | ⭐⭐⭐ |
| 8 | Portable interpretation transmitter/receivers | ⭐⭐ — unless you're supplying the system |
Your headset. You'll potentially be listening and speaking continuously for hours. A $50 headset that becomes uncomfortable, leaks sound, or produces mediocre microphone audio can cost you much more professionally than its purchase price suggests.
And I wouldn't make Bluetooth your primary interpreting connection. Wireless headphones are great for everyday use, but simultaneous interpretation is one of those situations where boring, wired, predictable equipment wins.
If you tell me your typical conference size (e.g. 20, 100, 500+ people), language pairs, whether you work onsite or Zoom/Teams, and your equipment budget ($500 / $1,000 / $2,500+), I can put together a specific freelance interpreter kit with exact models and current prices.
If you're starting from scratch, I'd spend the money in this order:
| Priority | Equipment | Approx. importance |
|---|---|---|
| 1 | Professional wired headset | ⭐⭐⭐⭐⭐ |
| 2 | Reliable laptop | ⭐⭐⭐⭐⭐ |
| 3 | USB audio interface | ⭐⭐⭐⭐ |
| 4 | Ethernet adapter + cable | ⭐⭐⭐⭐ |
| 5 | Backup headset | ⭐⭐⭐⭐ |
| 6 | Power bank/backup power | ⭐⭐⭐⭐ |
| 7 | USB hub/adapters | ⭐⭐⭐ |
| 8 | Portable interpretation transmitter/receivers | ⭐⭐ — unless you're supplying the system |
Your headset. You'll potentially be listening and speaking continuously for hours. A $50 headset that becomes uncomfortable, leaks sound, or produces mediocre microphone audio can cost you much more professionally than its purchase price suggests.
And I wouldn't make Bluetooth your primary interpreting connection. Wireless headphones are great for everyday use, but simultaneous interpretation is one of those situations where boring, wired, predictable equipment wins.
If you tell me your typical conference size (e.g. 20, 100, 500+ people), language pairs, whether you work onsite or Zoom/Teams, and your equipment budget ($500 / $1,000 / $2,500+), I can put together a specific freelance interpreter kit with exact models and current prices.
No sources cited
As a freelance interpreter, investing in or specifying equipment depends entirely on whether you are expected to provide a **portable/tabletop system** (for smaller meetings, site visits, or mobile setups) or partner with AV techs for a **full ISO-compliant booth setup**. For professional simultaneous interpretation…
As a freelance interpreter, investing in or specifying equipment depends entirely on whether you are expected to provide a portable/tabletop system (for smaller meetings, site visits, or mobile setups) or partner with AV techs for a full ISO-compliant booth setup.
For professional simultaneous interpretation (SI) at a conference, the gold standard equipment splits into distinct categories based on your operational needs:
Plantronics Go to product viewer dialog for this item./Poly Go to product viewer dialog for this item. or Sennheiser Professional Headsets Go to product viewer dialog for this item.: You need an ultra-reliable, crystal-clear double-ear headset with a noise-canceling boom microphone (e.g., Sennheiser's dedicated interpreter headsets or a robust dual-ear USB/XLR headset). Comfort for long stretches and pristine audio fidelity are non-negotiable.
USB/XLR Interface: A small portable external sound card or audio interface (like a Focusrite Scarlett Go to product viewer dialog for this item. ) to connect your professional mic/headset cleanly to laptops or mobile transmitters without buzzing or feedback.
Enersound Systems (e.g., Enersound TP-600 Go to product viewer dialog for this item. / R-120 series Go to product viewer dialog for this item.): Widely regarded for portable 72–76 MHz or digital FM setups. Ideal for small-to-medium mobile setups where you transmit to audience receivers.
Williams AV (PPA or Digi-Wave series): Excellent portable FM and digital spread spectrum (DSS) systems. Highly reliable, secure, and intuitive for audience members wearing pocket receivers.
Note: These are great for portable settings, but for major conferences, the venue's AV team usually handles multi-channel stationary transmitters.
WHC (Remote Simultaneous Interpretation platforms): Platforms like KUDO, VoiceBoxer , or Interactio are frequently used by event organizers for hybrid/remote delivery.
Dedicated Console Apps: If working remotely, a solid hardware backup internet connection (ethernet, not just Wi-Fi) and an external hardware controller or stream deck can help manage microphone muting rapidly.
ISO 2603 / 4043 Sound-Isolated Booths: For high-level multilingual conferences, you should never own this yourself—you rely on the venue or an AV supplier to provide full table booths.
Digital Interpreter Consoles (e.g., Bosch DCNNG Go to product viewer dialog for this item. or Televic Go to product viewer dialog for this item.): Featuring channel selectors, relay interpretation capabilities (listening to another booth if translating a non-floor language), and cough-muting buttons.
If you'd like to narrow this down, tell me:
I can give you a more specific gear checklist or advice on what to bill clients for.
For professional on-site simultaneous interpretation at a conference, the gold standard is an **ISO-compliant soundproof booth** paired with a dedicated **interpreter console** (such as Bosch or KUDO hardware), high-end **dual-muff headsets** , and an **infrared (IR) or radio frequency (RF) transmission system** for…
For professional on-site simultaneous interpretation at a conference, the gold standard is an ISO-compliant soundproof booth paired with a dedicated interpreter console (such as Bosch or KUDO hardware), high-end dual-muff headsets , and an infrared (IR) or radio frequency (RF) transmission system for the audience.
As a freelance interpreter, you rarely buy or haul these large full-room conference systems yourself; instead, you work with specialized AV providers or event organizers who supply them. However, knowing the industry standards ensures you can request the right tools for your safety and performance.
Essential On-Site Conference Equipment
Portable & Hybrid Equipment (For Freelancers on the Move)
If you are doing portable simultaneous interpretation (often called a "bilingual tour guide" or "bidule" system for smaller, mobile meetings), you need portable gear:
Remote Simultaneous Interpretation (RSI) Gear
If the conference is virtual or hybrid, you need robust home-studio or mobile remote gear:
If you're preparing for a specific gig, tell me:
I can help you review the technical rider or checklist for the event.
If you’re a **freelance conference interpreter**, I’d avoid trying to own the entire conference system. The best setup is usually a **high-quality personal interpreter kit that plugs into whatever system the AV company provides**. ## My recommended setup ### 1. Professional interpreter headset — your most important…
If you’re a freelance conference interpreter, I’d avoid trying to own the entire conference system. The best setup is usually a high-quality personal interpreter kit that plugs into whatever system the AV company provides.
I’d prioritize a closed-back headset with a good boom microphone, rather than ordinary headphones plus a separate mic.
A strong option is the
. It gives you good isolation, a professional microphone, and is designed for broadcast/production work.
Another excellent option is the
, particularly if you prefer a robust broadcast-style headset.
For the headset, look for:
I'd spend money here before buying almost anything else.
Bring a second pair of reliable headphones without a microphone. You may encounter consoles with unusual connectors, or another interpreter may need to monitor a channel.
A simple, rugged studio/broadcast headphone is sufficient. Don't rely on Bluetooth—wired is the professional choice for SI.
This is where a freelance interpreter can really benefit from having their own kit.
I'd carry a small case containing:
The exact connector you'll need depends on the venue's interpreter console, so don't buy a headset until you know which consoles you encounter most often.
For hybrid/remote assignments, I'd add a small professional USB audio interface with:
This is much more useful for a freelancer than owning an expensive conference console.
Bring:
But don't depend on a laptop battery for a full conference day.
I wouldn't recommend buying your own complete Bosch/Televic/Shure interpretation system unless you're also renting it out or acting as the AV provider.
A professional SI installation can involve interpreter consoles, central control, transmitters, radiators, receivers, booths, cabling and technicians. Televic, for example, sells complete professional interpretation infrastructure rather than merely an interpreter's personal workstation.
Likewise, a complete Bosch system is something an AV/interpretation-equipment company normally supplies.
For example, a Shure MXCIC console supports multiple outgoing and relay channels and is designed as part of the larger Shure conference system—not really as a standalone freelance interpreter purchase.
There's a different category worth considering: portable interpretation systems.
For small meetings, tours, workshops, factory visits, etc., a self-contained wireless system can make sense. The Williams Sound Digi-Wave INT system, for example, is designed specifically for portable simultaneous interpretation.
That can be much more practical for a freelancer than hauling around a booth and IR distribution system.
If I were building your kit from scratch, I'd do:
| Equipment | Priority |
|---|---|
| Professional broadcast interpreter headset | ⭐⭐⭐⭐⭐ |
| Backup headphones | ⭐⭐⭐⭐ |
| Adapter/cable kit | ⭐⭐⭐⭐⭐ |
| USB audio interface | ⭐⭐⭐⭐ |
| USB-C power bank | ⭐⭐⭐⭐ |
| Laptop | ⭐⭐⭐⭐ |
| Portable interpretation system | ⭐⭐⭐ — only if you provide equipment |
| Full interpreter console | ⭐ — usually rent/provided |
| Portable booth | ⭐ — usually rent/provided |
| Receivers for audience | ⭐ — usually rent/provided |
Bottom line: invest in the things that stay with you: headset, backup headset, adapters, cables, interface and power. Let the conference AV company supply the booths, interpreter consoles, transmitters and audience receivers.
If you tell me your typical conference size (e.g. 50, 200, 1,000+ attendees), languages, and whether you interpret onsite, remotely, or both, I can narrow this down to a specific $500 / $1,000 / $2,000 freelancer kit.
If you're a freelance interpreter, I’d **avoid buying a full conference interpretation system outright** unless you regularly act as the technical provider. Your best setup depends heavily on whether you're supplying equipment for a small meeting or working inside a venue that already has an AV/interpretation system.…
If you're a freelance interpreter, I’d avoid buying a full conference interpretation system outright unless you regularly act as the technical provider. Your best setup depends heavily on whether you're supplying equipment for a small meeting or working inside a venue that already has an AV/interpretation system.
1. A good interpreter headset — buy this yourself
This is the one piece of equipment I would absolutely own. Your headset should work with the console/interface supplied by the venue or AV company.
2. A portable interpreter console — optional but worthwhile If you frequently do smaller conferences where the client doesn't have a dedicated system, a portable console gives you much more independence.
The Williams Sound IC-2 is one example of a professional interpreter control console; it supports multi-language simultaneous interpretation and can work with FM, IR and Digi-Wave systems.
$2,189.00
A less expensive alternative is the Enersound IC-12, which provides 12 channels and relay interpretation and is designed for two interpreters working together.
$1,034.00
For small meetings, training sessions, factory visits, workshops, etc., a portable radio/digital system can make sense. Systems such as Williams Sound Digi-Wave combine transmitters/receivers and can be considerably easier to deploy than a traditional conference installation.
$18,389.00
This is particularly attractive if you're sometimes expected to bring the entire interpretation solution, rather than simply sit in a booth and interpret.
For a 100+ person conference, multiple languages, or a ballroom, I'd generally rent the interpretation infrastructure and have an AV technician handle it.
A professional system typically consists of:
Speaker microphones → conference audio → interpreter console → interpreter microphone → transmitter → infrared/radio receivers → audience headsets
For example, Bosch's INTEGRUS system supports up to 32 language channels depending on transmitter configuration and uses infrared transmission to distribute interpretation to audience receivers.
The important thing is that you generally don't want to be simultaneously responsible for interpreting and engineering a 500-person conference. Have the AV company provide the transmitter, radiators, receivers, consoles, cabling and technician.
For conventional simultaneous interpretation, acoustic isolation is just as important as the electronics. A proper booth prevents the interpreters from hearing the room directly and prevents their speech from leaking into the conference space. Bosch's documentation specifically references ISO requirements for permanent and mobile interpreter booths.
For a freelancer, I'd therefore think of your equipment in three tiers:
| What you own | What you rent/borrow |
|---|---|
| Excellent interpreter headset | Booth |
| Spare headset/earpieces | IR/FM transmitter |
| Adapters | IR radiators |
| Extension cables | Audience receivers |
| USB audio interface (if doing remote/hybrid) | Interpreter consoles for large jobs |
| Backup batteries/power bank | Full conference audio system |
| Small portable console, if useful | AV technician |
Don't buy equipment based simply on "simultaneous interpretation" in the product description. Conference systems use different connectors, channel architectures and signal standards. Your headset/console needs to be compatible with the system the venue or AV company is using.
If you tell me (a) typical audience size, (b) how many languages, (c) whether you usually work in a booth or at a table, and (d) your approximate equipment budget, I can recommend a specific freelancer kit with actual models and prices, from a ~$500 personal kit up through a professional ~$5,000+ setup.
Providing professional **simultaneous interpretation** requires a reliable, low-latency, and crystal-clear audio setup. The "best" equipment depends on whether you are doing a fully mobile/portable setup (infoport) or a heavy-duty multi-channel conference…
Providing professional simultaneous interpretation requires a reliable, low-latency, and crystal-clear audio setup. The "best" equipment depends on whether you are doing a fully mobile/portable setup (infoport) or a heavy-duty multi-channel conference setup.
Here is the essential gear broken down by category:
If you'd like, let me know:
I can narrow down a specific gear package and budget recommendation for you.
For a freelance interpreter providing simultaneous interpretation at a conference, the best equipment setup depends on whether you are renting a turnkey system through an AV provider or investing in your own portable gear . The gold standard for professional conferences includes a **soundproof tabletop or full-size…
For a freelance interpreter providing simultaneous interpretation at a conference, the best equipment setup depends on whether you are renting a turnkey system through an AV provider or investing in your own portable gear . The gold standard for professional conferences includes a soundproof tabletop or full-size ISO-compliant booth , a dedicated interpreter console (such as units from Bosch or GONSIN ), high-clarity infrared (IR) or reliable FM wireless transmitters/receivers for the audience, and a lightweight, noise-canceling headset microphone.
Essential Hardware Components
Portable vs. Installed Systems Comparison
| System Type | Best Use Case | Primary Advantage | Main Disadvantage |
|---|---|---|---|
| Infrared (IR) Systems | Single-room, high-security conferences | Superior audio fidelity; secure (signal won't pass walls) | Requires line-of-sight; disrupted by bright sunlight |
| FM Radio Systems | Mobile tours, multi-room breakout sessions | Easy to set up; signals pass through walls and obstacles | Susceptible to radio frequency/cell phone interference |
| Tour-Guide / Transceivers | Small bilateral meetings, depositions | Ultra-portable, lightweight, cost-effective | Limited channels and range for large ballrooms |
If you can share whether you are supplying the equipment for a large venue or looking for a portable kit to carry yourself , I can give you a more specific brand and model recommendation.
For a **freelance conference interpreter**, I’d build around a professional headset + a reliable interpreter console/interface, rather than trying to carry a complete conference system yourself. In most large conferences, the AV company supplies the booths, consoles, transmitters, and receivers; your personal kit…
For a freelance conference interpreter, I’d build around a professional headset + a reliable interpreter console/interface, rather than trying to carry a complete conference system yourself. In most large conferences, the AV company supplies the booths, consoles, transmitters, and receivers; your personal kit should make you compatible and give you a backup.
| Equipment | What I’d choose | Why |
|---|---|---|
| Interpreter headset | Sennheiser HMD 26 or beyerdynamic DT 297 | Excellent speech intelligibility, isolation, comfortable for long sessions, professional boom mic |
| Interpreter console | A compact professional console such as Enersound IC-12 | Gives you floor/relay monitoring and interpreter controls; useful for smaller events where you may need to bring the console |
| Portable interpretation system | ListenTALK or Williams Sound Digi-Wave | Good when you're providing the entire interpretation setup rather than just interpreting |
| Laptop | Modern MacBook/Windows laptop with USB-C | Essential for hybrid/remote events, terminology, documents, Teams/Zoom, etc. |
| Audio interface | Small USB interface with XLR input + headphone monitoring | Excellent backup when an event's audio setup is improvised |
| Cables/adapters | XLR, ¼", 3.5-mm, USB-C, USB-A adapters, extension cables | Conferences have an astonishing variety of connectors |
| Backup | Spare headset + wired headphones + USB audio adapter | A headset failure shouldn't end your assignment |
Your headset is the piece of equipment you use continuously, so I'd prioritize it over almost everything else.
$549.00
The HMD 26 is a particularly good professional choice: closed/on-ear construction, strong passive isolation, and a broadcast-quality microphone. It's much more appropriate for interpreting than a typical consumer or gaming headset.
A beyerdynamic DT 297 is another excellent professional option.
$499.99
I would not make AirPods, Bluetooth headsets, or ordinary laptop headsets your primary conference-interpreting equipment. Bluetooth introduces unnecessary latency/compatibility issues, and you want a predictable wired connection.
This is the biggest distinction for a freelancer.
If you're hired as the interpreter, the conference organizer/AV contractor will normally be responsible for:
speaker → conference audio → interpreter console/booth → interpreter → interpretation channel → audience receivers
In that situation, your personal equipment can be relatively compact.
If you're hired to provide the interpretation technology as well, you're effectively becoming the AV provider. That's a much bigger investment: interpreter consoles, transmitters, receivers, charging/storage cases, frequency management, cabling, etc.
For example, a Williams Sound IC-2 is a dedicated interpreter console designed for simultaneous interpretation and can interface with FM, IR and other systems.
$2,189.00
For a genuinely portable operation, ListenTALK and Digi-Wave-type systems are worth considering, but I'd rent rather than purchase a large system until you have enough recurring work to justify it.
$1,753.00
This is something I'd consider almost mandatory as a freelancer.
Bring:
The idea is that if the venue's console/interface doesn't cooperate with your equipment, you can still establish a clean wired audio connection.
For a small conference where you may need to supply the whole system, a portable interpretation package makes much more sense.
For example, the Williams Sound Digi-Wave 400 system is sold as a complete portable interpretation package with transmitters, receivers, microphones and earphones.
For 10–50 listeners, this sort of system can be much more practical than attempting to assemble professional RF equipment from individual components.
If I were starting a freelance simultaneous-interpreting business today, I'd go:
Tier 1 — essential
Tier 2 — once you get regular conference work 8. Professional interpreter console 9. Second headset 10. Portable interpretation/transmitter system
Tier 3 — only if you're supplying AV 11. Multiple interpreter consoles 12. Multichannel transmitter 13. Audience receivers/headsets 14. Charging cases 15. RF/frequency-management equipment and appropriate spares
One important caveat: if you're working in a conventional ISO-style conference booth, don't buy equipment before asking the AV provider what console/system they use and what headset connector/pinout they expect. The headset itself is the safest personal investment; the console and RF equipment are much more system-dependent.
If you tell me your typical conference size (e.g. 20, 100, 500+ people), whether you work in booths or portable setups, and your approximate budget ($500 / $1,500 / $5,000+), I can narrow this down to a specific freelancer kit.
- **Portable Transmitter (Tour Guide System)** : A lightweight, mobile radio transmitter (such as the [Williams Sound Digi-Wave Go to product viewer dialog for this…
If you'd like, tell me:
I can help you narrow down specific brand models or put together a complete gear checklist.
If you're a freelance conference interpreter, I’d **avoid buying a complete conference system** unless you regularly act as the AV provider. The best setup is usually to own the **interpreter-side equipment** and rent the venue-specific transmission/booth system. ### My recommended professional kit | Equipment | What…
If you're a freelance conference interpreter, I’d avoid buying a complete conference system unless you regularly act as the AV provider. The best setup is usually to own the interpreter-side equipment and rent the venue-specific transmission/booth system.
| Equipment | What I'd choose | Why |
|---|---|---|
| Interpreter headset | Beyerdynamic DT 297 PV MK II | Excellent isolation, boom mic, comfortable for long sessions, replaceable cable/pads |
| Interpreter console | Williams Sound IC-2 | Professional console that works with FM/IR/Digi-Wave systems |
| Portable distribution | Williams Sound Digi-Wave 400 | Excellent when you're doing smaller meetings without a full conference AV system |
| Full conference system | Bosch Integrus/DICENTIS | Best choice for large, formal multilingual conferences |
| Backup headphones | Closed-back studio headphones | Essential if the headset or connector fails |
| Adapters/cables | XLR, ¼", 3.5 mm, USB audio interface as appropriate | Conference AV setups vary enormously |
| Power | Small UPS/power bank + spare batteries | Prevents a surprisingly common failure |
| Accessories | Gaffer tape, cable labels, flashlight, USB-C hub, spare cables | Cheap insurance |
The DT 297 PV MK II is particularly attractive as your personal headset: it's closed-back, has a cardioid condenser boom mic, good ambient-noise attenuation and RF interference resistance. The North American model is currently listed at about $530 direct from Beyerdynamic.
The Williams Sound Digi-Wave 400 is probably the sweet spot. There are configurations intended specifically for interpretation, including a package supporting 4 languages plus floor audio and up to 50 listeners. It is much more portable than a conventional conference-center IR installation.
$16,078.00
For a more modest portable system, the ListenTALK family is also worth considering, particularly for small meetings, training sessions and events where you don't need dozens of language channels.
$5,039.00
For a 100–1,000+ person conference, I'd want the venue/AV company to provide:
floor microphones → mixing/AV system → interpreter consoles → transmitters/radiators → audience receivers/headphones
Bosch's Integrus is a very established professional approach: the interpreted channels are transmitted to wireless IR receivers, and the system can support large multilingual conferences. Bosch's current documentation describes up to 31 language channels in its conference ecosystem.
In other words, your job as the interpreter should ideally be to arrive with your headset and perhaps your preferred console/interface, rather than schlepping 200 receivers and an IR radiator to every gig.
For serious conferences, the booth is as important as the electronics. Current ISO standards cover both permanent and mobile interpreting booths; the 2024 mobile-booth standard is ISO 17651-2:2024.
You want:
The European Commission's interpreting facilities guidance similarly emphasizes soundproofing, air conditioning, lighting, ergonomic chairs and a complete view of delegates.
Have a personal "interpreter emergency kit." Your most valuable equipment isn't necessarily the expensive stuff. Bring:
And if you're interpreting for more than roughly 30–60 minutes, plan on two interpreters per language so you can alternate. That's normal professional practice for sustained simultaneous work.
If I were starting as a freelance interpreter today, I'd spend the money first on a really good headset + emergency kit, then rent the transmission system and booth according to the job. The Williams Sound IC-2 is a reasonable professional console if you want to own one as well.
$2,189.00
If you tell me (1) typical audience size, (2) how many languages, (3) whether you usually work in booths or small meeting rooms, and (4) your approximate budget, I can narrow this down to a specific $1,000 / $3,000 / $5,000+ freelance interpreter kit.