Randy...those who might have been pushing you toward this amp, and/or tubes in general; I think what they were doing...is trying to "f a t t e n up" your sound.
I'm not a fan, of the DAC-as-preamp approach. I've tried it, many times...and with many models; some, naturally, are better than other. But none of them, ever matched a really good pre-amp; for my taste.
IMO...the trade-off is this: DAC-as-preamp, and/or passive pre-amps, etc. Yes...the path is shorter, "cleaner", etc.; and that can result, in a very resolving sound. But it can end up being, what you might call...
too clean; too "sterile", and a bit thin. Going that route, with your Benchmark...and then into an
SS amp; that's kinda a "clean" on "clean" combo.
The VT-50,
should be lending
weight,
body;
meat...to the musical bones. The fact that you're finding that...
and, don't feel a loss of resolution at all (in fact, maybe find it...to at least
appear, even
more resolving); is a home run...and why ARC was a great choice (I know you are new, to the wonderful, strange, and maddening world of glass...but ARC is considered to be pretty "linear" sounding, for tube kit. I know you're not one, for messing-around...at least just yet; but know that KT-88s...and I'd HIGHLY recommend Gold Lions here
https://www.upscaleaudio.com/collections/power-tubes/products/gold-lion-kt88 ...would give a touch more warmth, body, and richness at a possible small sacrifice, of resolution. BTW...these are what you have now
https://www.upscaleaudio.com/collections/power-tubes/products/svetlana-sed-winged-c-6550c , except the cream of the crop from ARC!).
About the "few marks, scratches, etc."; I hope you mean mostly confined, to the
top? Those are from the previous owner...and yes; not egregious IMO, and to be expected as you said. But I really didn't notice much to anything, on the all-important face-plate?
Joe is right; TOOBS RULE! PICS!!