Tube amp for Sourcepoint 8?

Well, given you like the Exposure (nice amp BTW) and are just looking for a little more meat on the bones you might be looking for more of a neutral sounding tube amp rather than a more conventional and warmer “tubey” sounding amp.  I’d put the PrimaLuna more in the latter camp and would be a little concerned you might miss some upper octave detail and energy.  With what you stated you’re looking for I’d check out the Rogue Cronus Magnum iii for a tube amp and the Unison Unico series that are hybrid integrated designs with tube pre and MOSFET solid state amp sections.  Sound Approach sells the latter with a 10% discount and a trial period, which is nice.  Either should do a great job filling in what you’re missing in the upper mids while retaining what you like about the Exposure.  Just some ideas to ponder FWIW, and best of luck. 

GanFET amps have a “warm” presentation, but not sure if it’s offered in an integrated

Thanks for all the thoughtful responses, guys. 

Soix, we are very much aligned - the two amps that have risen to the top of the  consideration set so far have been the Cronus ("Dark" version) and the Unison Unico Nuovo (or Due). Just not sure how much of a step up they are from the 3510. I'm going to give the speakers another 100+ hours before I think about this at greater depth. 

Atmosphere, I have my dad's ST70 in storage. I had upgraded it with Curcio mods a while back, so it's a little less euphonic than the original (which works in my favor here). I wouldn't want a 50+ year old amp to be my main rig, but at least it can give me a starting point for differences. It's more likely that I'd have better sonic luck with a KT88-based amp than with the EL34s of the ST70, but I can at least contrast. 

Thanks again!

I'd suggest the Cary SLI 80HS and the Margules I-240. Plenty of tube power and sweetness. 

I currently have the Cary paired with Volti Razz, such a great combo for my taste. I like that Cary changed the rectifier stage to SS, (apparently helps with the syrupy nature of previous generations but keeps the warmth of the tubes). Also with the Cary one can switch between Ultra-linear and Triode mode on the fly.

I have heard the Cary with Sourcepoint 10's and enjoyed the session very much. It reminded me of when I worked at our local HiFi shop and we sold Cary and Tannoy. They were a very pleasing combo in my book.  

Thanks, Doyle. I love the Volti stuff - I got to hear a pair of Vittoras a few years ago at Rocky Mountain and was floored (that's where I first heard the Border Patrol DAC, which someone will pry from my cold, dead hands;).

I've always. been intrigued by the Margules. The 10s are a little more fussy in terms of pairing than are the 10s, but still manageable, I think, for either of the amps you mentioned. I appreciate the suggestions!