Seventh Circle Audio

I have just build 2 A12s and while one seems to be functioning normally, the other distorts very quickly and sounds dark/has less output. I inspected the solder joints, and everything seems locked in place. Things appear to be installed in the right places, so I am at a loss. How can I troubleshoot this?
Thanks in advance. Also, please speak to me as an electronics moron, which I sort of am.

Tim is currently helping me with this. Very nice guy.

I know this post was made a while ago, but I just built 2 separate A12s and one is having a similar problem. It seems to follow the SC25 op amp that I have, but I was wondering what the solution to your problem was so I can check to see if I'm having the same thing.

Thank you,
-Joel