Sorry for the delayed response. Milpai, i share the same thoughts as you do about this amp. Running through my Sonic Frontiers tube preamp, I feel like i have a great combination of both detail and warmth. The soundstage is very plentiful as well. I gotta say that this combination of BOTH xlr and rca connections really makes that combination wake up. Insofar as tube rolling goes, i was referring to the stock sovtek 6922 tubes that came with the preamp. I'd like to change (roll) these 6 to the recommended Amperex or Phillips equivalent.
My speakers are the next thing to be upgraded, but i really am not sure what to go for. Considering my appetite for prog rock, jazz and tech metal, I am keeping my eye on B&W 803's, Tyler Acoustics, Von Schweikert VR4jrs, Dali Ikon/Euphonia's.....but i am not sure if these are the right combination. I have no ability to audition these locally. What is the speaker choices that other A21 users enjoy?