Can I Pair Audio Reseach Ref 3 w/ the McIntosh MC2505 Poweramp?

You don't have your system posted or say what kind of sources you prefer to use, so it's difficult to give precise input.  If you're a vinyl junkie with a hot table, arm and cartridge, that's one thing.  If you're all-digital and into streaming, that can often be something else.  Much (if not all) also very much depends on your speakers.

Given what you've said, I'd have to agree with brf that making a major upgrade to your preamp could well reveal weaknesses in the MC2505.  It's not a bad amplifier as such things go, but it is quite a bit older and limited in power.  

You might be better served taking the ~$5000 total budget that would include the sale value of the 2505 and looking at a MC7100 and C2200 combo, for example.  Talking to the guys at Audio Classics could give you other ideas, too.

Good luck & happy listening!

Thanks for posting details about your system, Ruben.  Since you are running all digital sources, I'd strongly suggest you forget about the C2300 & C2500.  You would be paying for a very high-end phono section in both that you won't be using anytime soon.  While the C2500 has an excellent DAC, it is also well above your budget.  Even the C2300 is pushing that end of it.

Because you have Tannoys, you might consider going the other way around because they are comparatively efficient and stable:  Tube amp and SS preamp.  An MC75 with a D100 would get your digital from the BlueSound into a better DAC than the Rotel and you can do away with the Rega and MC2505 altogether.  Just a thought, but I suspect that you would be very, very pleased with the result and would be in your budget range.  

If you eventually choose to get into vinyl, you can look at a C48, C50 or C2500 to keep an internal DAC and get a good phono section.  Do keep in mind that vinyl is a super-geeky branch of audio and can get very expensive very fast.  It isn't just a phono section; it's a table, arm, cartridge, protractor, cleaning accessories, interconnect and more.  It's also fussy and requires a knowledge base.  Be sure you truly understand what you're opening yourself up for if you decide to take that plunge.  

With respect to mixing ARC and Mc gear, I know folks that swear by it and others that swear at it.  You'll see my rig is pretty much all Mc, but I was crafting a very specific solution that couldn't be readily accommodated by ARC (ARC was also well beyond my comfort zone price-wise).

An audition at a local Mc dealer would be a very good idea for you.  Most of them stock Mc, ARC, Sonus Faber and B&W now, and that would let you get a better handle on the kind of sound available in your budget range.  I again suggest you contact Audio Classics; they have a world of expertise dealing with your kind of situation.

Have fun & good luck!