My primary amp is a pair of Altec 1569A theater amps. WARNING-Using these unmodified in the home is dangerous as the 700 volt operating current puts out not insignificant amounts of radiation. My amps were gutted but for the case and transformers. They run at about 425 volts and the transformers are always barely warm to the touch. Six tubes replace the four and the two input tubes are 6GU7s with NOS RCA 6SN7s cathode follower. No one uses my 6BG6 output tubes. The amps are fully voltage regulated including the bias (very stable). It has four levels of adjustable feedback starting about 6db which I prefer. The internals have oil filled caps and there are 2 huge 3X7 electrolytic storage caps on top. They kill my EAR 890 amp. My second system has the best Dynaco 70 ever with tremendous bass control and dynamics. Again, moded to the central tap on the transformers with voltage regulated design including the tube bias and superior large electrolytic storage caps. Mr. Record says it’s the only good Dynaco 70.
I do not understand the "negative feedback" posts without describing what type of negative feedback. There is global negative feedback (my EAR 890 has none) and internal negative feedback which should be employed or else risk distortion. I think current VAC amps have 7 db of negative feedback and internal feedback. Another friend has a personally repaired RM9 ultralinear amp that sounds very nice. It’s in the design that counts, not the "modern" and "new parts design" that makes a great amp. True, my amps are radically different than most. Audio Research makes crude/primative versions of voltage regulated amps today which is inferior in the design in my amps sophisticated voltage regulation.
Please correct me if you think amps should have both zero global and zero internal negative feedback.