I'm playing a beautiful Chieftain 4x10 combo that I love, but I've noticed that it starts breaking up and compressing between 9:00 and 10:00 (even with single coils when I dig in). This seems a bit premature even for a 40 watter. When I use a mild boost it go into classic rock territory and sounds great, but I'd rather have that happen when the volume is cranked closer to gig levels. Again, I'm not talking much above bedroom level here. For a comparison, my D13 FTR37 maintains composure until it's between 10:00 and 11:00 (which is much louder than the Matchless at the same level). The D13 sports 6V6's, but I just thought I'd share the point for arguments sake. Phil (Matchless) just set me up with new power tubes (JJ's) and I'm thinking that it may be time to try some options. Suggestions??