Rega Brio-R Break-in time.

@50jess
Do you really want to void a Rega warranty? Caps are relatively simple to replace, but opamps are surface-mount. A real challenge. Maybe you could await a Rega factory mod (if it should arise)? Or select a different amp?

JMTCW. I've compared the Rega Brio R with Brio 3, its immediate predecessor, side by side, over an extended period, say 50 hours. I am very familiar with the Rega family sound (having spent over 30 years in audio). The Brio R sonic character is vastly different from the Brio 3. I concur with mezzanine and others who are concerned with the Brio R displaying metallic harshness in the upper-mids and treble. I also feel its overall presentation is sterile, distant, spatially-constrained and lacking air/bloom in comparison to my references (Canary tube pre-amp, Atoll FET power amp, fed by Oppo 93 and custom DAC, powering Merlin TSM monitors, Huffman ICs and Clear Day speaker cables). In examining the Brio R's pre-amp section Rega appear to have installed an ancient TI TL072 opamp on line-level duties with what appear to be cheap Arcotronics(?) polyester 2.2uf input coupling caps. These components differ from the Brio 3 which appears to use a JRC opamp and Evox MMK input caps. These two aspects are likely to shape both amps' sonic characters significantly. I do hope Rega designers at least consider modifying the Brio R's front end for enhanced musicality. To be fair the Brio R's power amp section does a great job of delivering dynamics, grip, extension and PRaT. But this prowess cannot entirely compensate for that other perceived sonic shortcoming. Unfortunately it makes the Brio R tiresome to listen to, and does not quite fullfill its undoubted potential. YMMV. Enjoy the music!

IMHO Vienna Acoustics Mozart Grand's are highly musical speakers that are finely balanced. Electrically the Brio R would suit, given its claimed load stability down to 1.7 ohms. The rest of your system's synergy is important, including source components and cabling. See my earlier comments as to Brio R sonic character.

@Cableplex
It's a shame regarding this slight issue with what could be a killer amp. Perhaps it's unwise to lump all polyester caps together as sonic grunge. Remember earlier Brio's featured Evox MMK polyester box caps, and their interaction with warmer-sounding JRC op-amps obviously produces something more pleasant than the current Brio R pre-amp component choice. In time I hope Rega listen and learn.