The Tubes4HiFi ST35 is my current amp in use. Clean, punchy, dynamic, and extremely musical. I built a kit decked out to the 9’s including massive choke in the power supply and painted a custom chassis root beer brown. So far I can tell, the toroidal OPT make for a clean and dynamic sound as this certainly isn’t your grandpa’s tube amp from the 60s.
10/10 would recommend.
-Lloyd

