In-wall audio switch / volume control?

My goal is to install in-ceiling speakers in my bathroom and be able to listen to 2 sources:

1. zone-2 (rca) output from another receiver
2. local input

I'd like to have the local input in the wallplate as well. My goal is to be able to plug in my phone or mp3 player via 3.5mm cable while I'm in the bathroom and just have it sit on the counter. But I'd also like to be able to listen to the zone-2 output from the living room receiver. So ideally I'm looking for a single-gang wallplate with volume control and a simple input switch. Does something like this exist? The closet thing I've seen is from a proprietary system that would require me to purchase the matching amplifier.

My receiver that I will be using as an input is already AirPlay ready, however I would like to be able to play music from non-Apple sources as well. Too far away for Bluetooth.

I dont want the amp in the wall, just the source selector. Also dont have to have the local input in the same wallplate as the source selector. I can just add a standard 3.5mm keystone jack on a seperate wall plate for that. The main thing is the source selector. All the ones I've found are for use with speaker level inputs, not line level.