Newbie Question

I wouldn't bother with vintage amps. Yes, some were built to very high standards, some were not. Problem is it can be difficult to determine just what you're really getting when buying a vintage unit. Sellers can make all sorts of false claims about a unit's history and condition. 

If you want a great modern amp that is built to high standards, with high quality parts, you need look no further than a Yamaha A-S801. These easily compete with some of the best vintage receivers. Some of the newer Marantz integrateds are also very nice. 

If your speakers are really that high of sensitivity (not likely), you can get away with a solid-state amp of low power. Personally, I prefer SS amps with at least 75 watts/ch, even with efficient speakers. That seems to be the power sweet-spot, where less power often results in compression at high volumes, and more is often not necessary, especially if the amp has a robust power supply.

 Coming from the HT world, if you're ditching an AVR, you might be very surprised at how superior a good integrated amp can sound, even something as inexpensive as a Yamaha A-S301. If you care about having a tuner, the R-S700 is also a very nice unit with plenty of grunt.

Good move, HT is a wasteland of bad sound. Stereo integrated tube amps are the sweet spot of high end audio. Its what I've used for about 30 years now, and that was after extensive comparisons including some time with a McCormack DNA, one of the better SS amps around. Don't even consider receivers, vintage or otherwise. Or if you do consider them then at least take the time to hear one head to head against an integrated. That will be the end of your consideration period. And good riddance.

50 watts in a tube integrated is plenty, especially with your speakers. The thing about tube amps, everyone focuses on the tubes when really its the transformers, circuit, caps and connections that make all the difference. Go listen to two different amps that both use the same tubes and you will see instantly what I mean. Yes its true KT88s do sound different (a little more silky and 3D) than 6550s which sound different than the seductively smooth midrange of EL34s. But go and listen. You will see. You can't judge by tubes alone.

New vs vintage is harder. A lot of the appeal of vintage gear is, quite honestly, nostalgia. Which is fine. If that's what you're into. I mean that. Some of that old gear, nothing will ever look any better, and even then there's the undeniable appeal of that which has endured. What's new is new for a millisecond. What's good is good forever.

So you want to be selective. Especially with rebuilt. Anything gets rebuilt and you can forget whatever was before the rebuild. All that matters is the extent and quality of the parts and the skill of the rebuilder. Which could frankly be you. 

That's one of the beautiful things about tube integrateds. Open one up, what you see is what you get. You could literally build one super killer amp all by yourself and knowing nothing simply by patiently replacing one part at a time. All you would keep are the transformers, chassis, and knobs. Everything else is point to point wiring. Caps have values printed right on them. Resistors, ditto. Diodes, all standard stuff. 

If the thought of that turns you off then probably you should be looking at new, or rebuilt with a real good warranty. Because an old vintage tube amp is bound to have you doing that kind of thing anyway. Or paying someone else to do it.... eventually....

And oh, what you said about the build quality of vintage gear being unrivaled? Not even close. Remember: nostalgia. Take off the rose colored glasses, see the cheap screw terminals for what they are: cheap screw terminals! Amp designers just aren't the lazy profit mongers they're made out to be. Well not all of them anyway!

Nostalgia is very expensive, IMHO. Better to get some modern tube gear, or a sweet Japanese solid state integrated.

Best,
E

97dB will play loud with even a few watts. Depending on budget, speaker quality, and wherewithal, you could jump straight into a nice SET. If that's not for you, any tube integrated or power amp will be a massive improvement over solid state receivers.