I'm building a practice amplifier for my girlfriend who is learning to play the bass guitar. I'm a reasonably experienced electronics builder so building something to plug a guitar and headphones into is very simple.
What I would also like to do is add a TRS input so she can play along to her iPod/anything with a stereo output. This signal does not need to be amplified as it will be going straight to the headphones. The amplification circuit for the guitar is based around an LM386, much like this:
But with both headphone cables connected to the 220u capacitor instead of one speaker. It works well. I also need the stereo input from the iPod to go into the headphones, but without any drop in volume for either source. What is the simplest principle to do this?