Tube amplifier upgrade suggestions welcome.

Would you consider a used Raven Nighthawk integrated to be a better move than buying, say, the Parasound A23+ new and using my m2si as a preamp? This is kind of where I'm at decision-wise.  

My answer to this question was to stay all tubes and not  buy a Parasound.

Separates is a great way to go.
Use the m2si and find a used tube power amp. Quicksilver comes up for sale pretty often.

A rebuilt Dynaco by Will Vincent is a great amp. It has that classic tube sound.
https://www.audiogon.com/listings/lisa2a90-dynaco-un-limited-by-will-vincent-mondorf-caps-tube

A very highly regarded amp...
https://www.audiogon.com/listings/lisa8h87-music-reference-rm-10-mkii-tube

I would consider a tube integrated. Quicksilver and Raven are great options having a true tube preamp stage. Some integrated amplifiers have passive volume control. The Line Magnetic and Pass Labs integrateds represent the passive type. Both highly regarded. 

Check out Black Ice tube amps (Jolida) as they're underrated gems...I used a Jolida 502P power amp for years and it was a very powerful and clean tube bargain...and you can call the Jolida/Black Ice guys with questions...either an integrated or power amp will be within your budget.

Ok, thanks guys!  I know very little about tube amps but I have super high efficiency speakers and I think I'd like tubes -- we'll see!  :D  I do believe the smartest thing for me to do is to go used and trust what you, the experts, say is a great buy so that's what I'll do. 

I'm still leaning towards just an amplifier rather than an integrated because it will give me a better upgrade path, so I'm considering either of the two on Audiogon posted above. Thanks to @lowrider57 for the help!

I'm not sure I can afford one of these until the next round of stimulus money comes.  But maybe I can.  Not sure yet.  If I don't get one of the ones listed now can I come back and ask about other tube amps that might show up here or on other sites?