Line in issues on amp

Chairs

I’m retroactively amending all my comments for privacy’s sake. I know they’re cached in places, but this is still a best attempts effort. Mods - if any rules have been broken, please revert this post.

ICBM

The output impedance of the phone is too low for the amp's preamp to cope with and it's being loaded down.

You can fix it by adding something like a 100K resistor in series between the Line Input and where it joins the signal path.