Could the problem be the sovteks? If you will notice, many manufacturers put sovteks in to keep costs down. However, have you ever seen people "rolling" with them? Yuk! Sorry to say but I think you are doing a great injustice to some nice amps by using those tubes. Yes, I know it's my opinion but I've owned a lot of tubes and never like sovteks. They don't have the detail, warmth, dynamics or build quality of many others out there. That's why they are cheaper than most.