Hi, sorry for the long delay, I've been waiting to get chance to have a good look at this. I opened it up and checked the decibel levels. Unless I'm misunderstanding something this is what I did and saw:
All this was done with the volume pot up to full.
I checked the volume level at the main out: -18 db
checked same at headphone out: -13 db
using bulldog clip leads grounded the jack lead going in to sound card, put the other part of the jack across the 3 pins of the volume pot:
pin nearest edge of board nothing happens (guess its ground?)
middle pin and innermost pin both -22db
Sorry if I'm being a bit thick with this, thought 'hey, its a bit of soldering, how hard can it be!'. Guess I was wrong! I'm really stuck so appreciate all the help.