I'm not trying to rock the boat as I have broken in many items (including tubes) but 400 hours for those tubes seems a little crazy. Do you think other tubes in your system may have become weaker which caused the KT88's to get soft?
kt 88 shungyang treasures in mc275
I have recently installed the treasure kt 88 in my mc275. I am noticing tube glare that was not there with my original tung Sol 6550 tubes. They also seem to be a bit forward in presentation in comparison. How long does it take these to break in? Or, is this the sonic signature of these tubes?