With the KT-88s and modern parts including solid state rectification it's really a 4-55. This 5-20 circuit was created in the mid-Fifties by Mullard to introduce their EL-34.
The guys at Diyaudio.com, Eli Duttman, Boy Wonder, Taj, Johann Pottgeier and others collaborated, as they do on many designs. Steve Brown and I decided to collaborate on this as we did on the 45 amp. After 2 years of correspondence and finally my trip to Portland they were done this past October.
With Steve's guidance the EF-86 input tubes are wired in Triode, the Negative Feedback is removed and compensated for by input resistor padding. Gold Lion KT-88s make these powerful amps yield single-ended tone and texture while providing massive damping and drive to the JBL woofers.
