Those voltage deltas are around 3-5%. What is the delta of VARIAC to FULL power? I thought it was more like 25% 120 to 90 V.
I lived on Germany for a while and had a few power converters. I thought they converted Hz also but maybe I remember wrong. Anyway, my 120V/60Hz tube HiFi amp worked great with the converter. Could you hook up the Mark V to a voltage converter? Or did you get the Mark there in Europe? I used a Marshall Haze 40 for the 3 years I was there. Actually, I used 3 because they kept failing and the dealer gave me replacements. At the end, I got a full refund because the third replacement failed. So, 3 years and a free amp! Can’t believe how crappy that amp was. Strange thing is I miss the clean channel of that amp, it was something else. But I digress.....
