I do have to say that my old 1972 Randall has four 8417's and it puts out 170 watts. In it's day, this tube was rated at 50 watts. Supposedly, four of them made 200 watts. Randall decided that it would be better to throttle the tubes back a bit and rated four of them at 150. These are special, high output tubes that used to be in some of the finest hi fi tube amps. I tried to sell it a couple of times, but no one wants an amp that they can't get cheap tubes for. 8417's are about $80 a piece when they are listed on Ebay. I've seen matched quads go for over $450. Need I say more? Oh I will. You could put some good tubes in the Bugera and the tubes would be worth more than the amp.
Marty