Put a matched quad GL KT88 in my Yaqin 100b. Could not believe how good they sounded. Within 2 months, two could not register a bias, a third went alarmingly hot and orange and blew a channel (resister). My learned repair person was very anti this GL reissue. Replace them with JJ's. I'm back, but it's going to be hard being satisfied without that GL reissue sound, but they are just too expensive to keep replacing. What's better than these JJ's?
Pooty
Pooty