Peripheral onlY:

RF links largely exist from what you say.
If you are adding any new ones they may need to conform to an existing
statndard.
If not, consider the transmission  of digitised audio rather than
analog. Probably no more $ costly if worked at. Data is then in a form
that it can be manipulated as is with digitising having been done at
source and not on a per receiver basis. Digital "just works" or "just
doesn't" more or less - and with error detection and./or correction
you can decide  behaviour in marginal conditions. AM fades nicely in
marginal situations (eg try an AM portable phone - inserting head in
'beam' can make a difference). FM not so bad.
--=20
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