Considerable. At least there was a considerable diff from the VK500 vs. VK60 or such was my exp with those two amps.
I prefered the SS over the tube amp. I felt the tone of each amp's role was actually reversed IMO. The SS amp was silky smooth, yet robust and dynamic. Extended and quick. the VK60 tube amp had more air and was thinner up top with far less bottom end. Both were played on vSA vr4 JRs... and I own tube amps now. Apart form the output tubes all tubes were NOS RCA & Tungsol.
Of the two I'd have no trouble owning another VK500 w/BAT pk. Run xlr or with rca adapters... that amp sounded great IMO. Sometimes ya don't know what ya got till it is gone.
CAn't speak to the current models. Sorry. Good luck.