ARC VT-100MKII to MKIII, upgrade worth the cost?

I love my Mk-III but wish I'd gone for an LS-25 Mk-II and a good solid state amp (Bryston 4B-SST, Gamut, etc.). Yes the $850 retubing charge seems like highway robbery! It's Upscale Audio for me next time around!

Mrwigglewm, that's exactly what happened to me, I tried to replace the driver tubes with JJ Tesla E88CC and blew the resistors and a transistor near the closest tube to the faceplate. These Teslas would not bias in VT-100MKII. I would probably not mess with driver tubes any more, however your describtion of Mullard sound is very tempting. Audio research is installing the 6922 for me. But I will try the KT-88. I talked to Kevin Deal at Upscale Audio and he actually recommended the new Electro-Harmonix KT-88. They are supposed to be even more dependable the Svetlanas.

Gvatchna, I'm glad I read your response. I was going to try the JJ Tesla 6922. Did ARC comment on whether the electrical characteristics of the JJ are that different from the Sovetek? Did you actually adjust the input bias controls? I know how to do this after an intensive learning curve, but I would not recommend this procedure to anyone unless they are used to working on electronics, and, in addition, have a lot of patience and are willing to learn a number of things in the process.

Kevziek, the resistors smoked right at the moment when I started adjusting the bias. ARC just commented that the tubes are simply bad, I am not sure if it's true or not. I think Teslas draw too much voltage. The voltmeter went quite crazy. After my experience, I would not recommend JJ teslas for that amp and stick with the best vintages of 6922.

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.