I thought I'd start a new topic to see if anyone can help me in my search.
At the moment I'm doing radios (No. 2/3 in the biz) on a couple of musicals and am looking for a way of listening to audio coming out of the 30 odd receivers (Shure UHF-MA's & Sennheiser EM3532's) without employing a console or wearing out my headphone jack constantly plugging and unplugging. At the moment I'm using a 'home-made' switcher that I found out the back of the shop that I reckon someone knocked up years ago for this exact purpose. The problems is the rotary encoder used for selecting the input is noisy and doesn't always work and the crosstalk between inputs is terrible.
So my question is if anyone knows of any commercially manufactured products out there that could help me? I know a few of the larger theatrical audio houses around the world have manufactured their own devices for this purpose, but aren't (as far as I know) willing to sell them.

With 30 mics it sounds like you have some money.

Lowest cost is a load of 1u rack mixers, like Australian Monitor do something suitable. You need to either daisy chain or use a mixer with multiple unit linking.

Next step up is several Kramer VS2481 daisy chained

Finally, the pro way, use either SoundWebs or Symnet boxes as switchers, and StarDraw running on a PC or lappie, or if you are really adventurous, an AMX or Crestron touchscreen system. You will need to do some programming. When you've done it, sell it!