ARC VT100MK1 owners help...

The MkI is not as highly regarded as the MKII due to it's too small power supply.

Maybe this will help, Audio Review website has 29 reviews from owners of this amp.

http://www.audioreview.com/mfr/audio-research/MPR_589crx.aspx

Re-tubing this amp can be a bit of a chore.

http://mycollins.net/audio/artube1.html

Nice amps.......

I owned the Mk-I. I liked it.
Traded to the Mk-III. I liked it too.
The Mk-I has one bias trim screw per side.
The Mk-III has two bias trim screws per side and 6H30 input tubes.
Two screws per side allows for finer biasing.

I use solid state amps now.
I think solid state does a better job in a power amp application.

Tubes are still the way to go in a pre-amp, however.

Thanks for the info men,very helpful,Bob