Connect a microphone to Senheiser 120 wireless headphones for hearing impaired father

[dwinmt]

My dad is 95 & very hearing impaired. We have several sets of senheiser 120 wireless headphone base units positioned thru out the house attached to different Tvs. He can hear with these exceptionally well, way nicer than audio thru his hearing aids.

What I would 'like' to do is connect a wired microphone to 1 of the transmitter units audio inputs, ( it has a cable with male L/R RCA jacks) so that the unit (which would be closer physically to dad than the TV unit he is listening to at the time) would override that transmission and he would hear my voice in stereo. I'm thinking it would have to be some kind of powered microphone, with a on/off switch.

Is such a thing even possible, or am I barking up the wrong tree? If it is possible, could you please direct me to the hardware necessary?

 

[dudio]

I imagine the wireless base units have some kind of amplification. If that's the case, you could either get a simple mixer that you would have sharing the mic and tv sound input, or even a simple switcher to choose one or the other.