i've owned the Vitus SM101 several years ago.
these amps are quite sensitive to power cords.
must've tried a dozen power cords on these amps (including PAD Dominus, Nordost Valhalla/Odin, top of the line Acrolink Mexcel, Vitus Andromeda. Jena Labs, Jorma Prime, Pranawire, Kondo KSL-ACz, etc., etc.) during my ownership. from what i recall, PAD Dominus was pretty decent, but i liked Jorma Prime power best.
avoid the "brighter" sounding power cords (eg. Nordost Valhalla, Acrolink, Kondo)... very bad match!
"avoid the "brighter" sounding power cords"
same think also with speaker cables and interconnect?
what brand/model you used?