I have the Auricap version of the 21A and it is a wonderful amp. The 21A actually comes with mullards, I got a new set from upscale and they are identicle to what came with the amp. I just got a set of NOS RCA's from vintage tubes, (circa 1950's) but haven't tried them yet. The amp itself is very detailed, very musical. The Dynaudio 25 can be very mildly forward by some reports, I have not heard this with my system, (posted), nor have any of my friends. I travel a bit and am always listening to other systems, chronic upgradeitis, and I always come back and prefer my system. I think the belles really brings out the best in my system and highly recommend it. The closest pairing that I liked was the VTL 5.5 and 150stereo amp. I also auditioned Classe, YBA, BAT, MacIntosh.