I recently bought a used Audio Research Classic 60 amp (6550C tubes) on ebay and swapped out my McCormack DNA1 dlxe. Whew. What a difference. The McCormack is a great SS amp; quick and punchy with great bass, but the ARC tube amp has something special. The soundstage kind of envelops and then swallows the room whole. There's that fantastic tube "bloom" and the details of the recordings suddenly separate into distinct sounds and rhythms I hadn't noticed before. I'd had an ARC VT60 years before but I'd clearly forgotten how sublime tubes can sound.
Now I'm thinking of making a diy impedanzer for my Grados so I can jack my 'phones directly into the amp output
BTW, for any Gilmore owners out there, the Gilmore/DACT Preamp/ARC Classic 60 combination is a match made in heaven!
Of course, I still like solid state and I'm keeping my McCormack, but my recent tube experience has been a real eye-opener.
Makes me kind of envious now of all you RKV owners out there...