Gawan said:One mixing device I looked up last year already:
http://www.amazon.de/dp/B000J5Y214/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid=1TQ1MD8DDU0WY&coliid=I2F6FBSSGZ0GMR
Mixer
We use this one for our two radio studios: Behringer Xenyx X1204 USB http://www.amazon.de/Behringer-1204FX-Mischpult-USB-Audio-Interface-12-Kanal/dp/B0039PPW60
Product website with data sheet: http://www.music-group.com/Categories/Behringer/Mixers/Analog-Mixers/X1204USB/p/P0A0H
In general, there are some tricky issues with USB audio routing between PC and mixers, which are not always straightfoward to solve. But this mixer is guaranteed to work because it can 1) put USB input on the headphones, and 2) send microphone audio via USB at the same time.
Mics
We have Sennheiser e840 condenser microphones (XLR). These may not be available any more (haven't looked much though). Any equivalent XLR condenser mics should work, but don't go overboard with the price. Lower priced ones should be enough, especially if you tweak the equalizer.
We also have foam thingies on them to pre-dampen breathing noise a bit. The mics are mounted in shock absorbers (something similar to this) which are mounted on flexible arms (similar to this).
Headphone output
The mixer has only 1 headphone output. If you have several hosts sitting on a table, you'll also need a headphone multipier so that everyone hears the same audio. We have this one: http://www.amazon.de/Samson-SASAMP-4-Kanal-Stereo-Kopfh%C3%B6rer-Verst%C3%A4rker/dp/B0002ORPU2 . It works with 6.35 mm stereo Phone connectors. You could use 6-to-3 mm Phone adapters if you have different headphones.
Dynamic range compressor
This is optional. You need it only if you want to filter out background noise that you cannot avoid (like a busy road outside). We have this one: http://www.amazon.de/Samson-S-com-SA-SCOM4-4-Channel-Compressor/dp/B0002D0672 But the Behringer mixer has a built-in compressor that is lower in quality, but should do the job just fine in the beginning.
Cables
4 x XLR cables male to female (if you have 4 microphones)
1 x 6.35 mm stereo Phone connector cables (to the headphone multiplier)
2 x 6.35 mm mono Phone connector cables (optional, to and from the range compressor)
1 x USB cable
PC
Must be PC (laptop or desktop), not too young, not too old. Ideally you send us a new SSD hard drive (120 GB is enough), you'll get it back pre-installed with Debian 8. It needs Linux because it supports arbitrary application-to-application audio routing, and has one custom piece of software that makes the automation of a radio show more easy (has to do with starting/stopping the show on time, plus archiving it on Sott).
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The mixer would be the most important part because it interfaces with the PC, and we have the right settings for it. The rest of the equipment is up to you. The above is just a suggestion, so as always, you should check compatibility before you decide for something, and ask if you are unsure!