Solid state amp that tube fan can be happy with?

One significant factor of tube amps is a low damping factor which interacts with speakers to change their frequency response(which includes fuller, softer  mid bass). Almost all solid state amps have a high damping factor due to usually higher feedback than tube amps which doesn't interact. One solid state company with a great rep is Pass Labs which have a low damping factor like tube amps and will interact with speakers the same way as tube amps.

I travelled a similar path.   For my ears, I found the NAD class D amps to be extremely quick and detailed, but lacked the tube warmth I love.   Krell was the answer for me.   I love the Krell sound as it is like tubes yet has more authoritative and controlled bass.   YMMV.

Ayre

I’ll say Hegel, close enough for me.  My tube amp is an ARC VSi 75.

Coda 5.5 Pure class A amplifier 50 wpc 8 ohms , 100 into 4 ohms 

and priced right $6500 retail call Mike audio archon for a fair deal