Hi Russ66,
I too purchased BIAB for making backing tracks to songs I wanted to play live while singing and playing my acoustic guitar. I also have a Fender Passport I use. My Passport is older and has an aux in which takes a 3.5mm stereo input. I have used an iPod and PC (with BIAB) to play live. I can't be positive, but I am pretty sure the mix (supporting tracks) comes through as stereo.

I know the elderly love to hear the vocal harmonies in music, which takes them to a time that the voice was the primary instrument they heard. I took a different approach to this.

I purchased a TC Helicon Voicelive Play GTX, which duplicates your voice and adds up to two additional parts for harmonies. Works really well and fairly simple to use. It uses the notes in the guitar chords to generate the harmonies. It is a foot pedal in which one button turns on and off the harmonies. Look it up on YouTube.

The Voicelive play has two xlr outs. I have mine set in stereo and run the right to channel 1 (panned right) and the left output to channel 2 (panned left). The result is a nice stereo mix that separates the harmony parts. The guitar and vocals can be adjusted in the gtx so all you need to be concerned with is the mix from your BIAB.

I set the BIAB on Jukebox which allows you to play one song after the other in the Order you want. It can be started and stopped with the touch of the space bar.

Good luck on your search for this information. I am sure you will find something that works great for you.

And thanks for your service of singing to the elderly! I am sure whatever you deliver is wonderful to them.