Thanks. Unfortunately, while making up the new board yesterday, I discovered that a cut and jumper were in the wrong spots. Here is the corrected layout (my apologies to anyone that may have already cut a board);
Furthermore, reducing C3 also helps with any possible HF oscillation that may present itself. Even with the decreased C3/increased C5, there's still plenty of top end crunch on this sucker.
I rolled a few different tubes through this the other day. Some new JJ's, some older Tung Sol's, and old Mullard, GE, and RCA's as well. Each gives a slightly different edge to the top end, probably because of differences in the clipping knee. To date, I've only tested this through my little 15watter SS test amp. I'm anxious to see what this will do with a 100 watt OD channel.
Using a a TO-99 can (LM1458) for the op amp. I've used it before in another project, and it sounds as good as it looks.
Going to try and finish boxing this tonight.