Tube amp recommendations to drive Paradigm Tributes

I am looking for recommendations for a decent reasonably priced Class A / Tube amplifier for my listening room. I currently have an integrated Peachtree Nova500 driving a pair of Paradigm 30th Anniversary Tributes.  The Nova supposedly outputs 500 watts per channel (into 8 ohms). The Tributes specs say impedance is  "compatible with 8ohms" I'm not exactly sure what that means. Regardless, the system sounds very good and I enjoy it. However I am very curious about class A/tube amps. Last year I listened to a Bob Carver Crimson 275 amp and was very impressed. I wonder if that would be a good match for the Tributes. Any input would be appreciated.
Are you wanting an integrated amp or an amp + preamp?  What is your budget?

I'm planning on using my Nova 500 as the preamp, unless I find a better integrated solution. Budget is wide open at this point.

Regardless, the system sounds very good and I enjoy it. However I am very curious about class A/tube amps.

You will drastically change the sound you say you enjoy so much by going from Class D SS to Class A tube.  I'd be surprised if using the Nova500 would provide a magical pairing when using it only as a preamp to the tubes.  I'd definitely buy your tube amp used so you can sell close to break even if you decide the synergy isn't great.  You're just tinkering to see what other sonic signatures are all about and there is nothing wrong with that but it doesn't sound like you're being very deliberate to try to see what tube magic is all about by cobbling together new and existing components that are just handy for you.

You're probably right about the Peachtree not paring well with a tube amp. I like the DAC on it. But I want to really hear what a fully Tube system can do. So all that aside maybe I'll check out an integrated Tube amp.
I'm not familiar with those speakers, but according to specs found online, they appear to be relatively sensitive, which means you may be able to get by with 35 WPC.   If you're not on a budget, I'd be looking at Jadis and Airtight.   Still very good, but not as pricey are Octave, Line Magnetic, Leben, VAC and VTL.  Reputable integrateds on a budget can be had from Rogue, Cayin and Jolida.  EL34 based amps will typically give you a more tubelike euphonic sound, whereas KT88 based amps are a bit more neutral, but still are much more enjoyable than solid state offerings IMO.  US Audio Mart has a decent selection of used tube integrateds.  Listings of note include VAC Avatar and a Leben... but I'm not sure if they'll be powerful enough for your speakers.
I've heard the Tributes at a dealer many years ago.  They are a terrific speaker.  I compared them against an A'gon favorite and was stunned.  They ate the competitor's lunch.  IMO.  

Ok, ... when I A/B'd the Tributes, the dealer used an ARC VS 115 trade in.  He used that to drive the Tributes and the competitor speakers.  My amp, an ARC Ref 150 SE, shares a similar ARC house sound with the VS 115.

Bottom line:  the Tributes are very sensitive.  You don't need tons of power.  If you want to hear magic, try an ARC tube amp, preferably a new'ish  model that uses KT-120 or KT-150 power tubes.  Pre-owned is fine.  Drive the Tributes off the 4 ohm taps.  You will get a flatter frequency response and deeper, tighter bass because the output impedance off the 4 ohm taps is relatively low; lower than the 8 ohm taps.

I realize its hard to do meaningful comparisons unless you can match the Tributes with an ARC amp and compare it to other amps, so consider my comments as just a data point.

In short,  I think the Tributes and a modern ARC amp make for a magical combo.  IMHO.