I own the VT100 MKII. With NOS 6H23 (type 3 6922) from Upscale audio, the VT100 MKII equals the MKIII in terms of slam, basss solidity and dynamics. However the MKII is more liquid and musical. The MKIII tends to be a little "dry" sounding. The VT100 MKIII reminds me of the older Classic series (60, 120) which were also hybrids. I disagree with Leonard: In my opinion, the VT100 MKII is the better amp for music enjoyment, although the VT100 MKIII may be "technically" better
You should not replace the input tubes without proper biasing. Biasing is tedious and difficult. Without proper adjustment, the output tubes will arc and blow the 1 and 100 ohm resistors (which are essentially fuses in the plate and grid circuits). In addition, the input tubes require tight tolerances and close matching.
You should not replace the input tubes without proper biasing. Biasing is tedious and difficult. Without proper adjustment, the output tubes will arc and blow the 1 and 100 ohm resistors (which are essentially fuses in the plate and grid circuits). In addition, the input tubes require tight tolerances and close matching.