Arcam A28.
On the other hand, the rep from Monitor Audio wanted me to get a $3500 amp (Moon Audio something or the other), because anything else 'didn't have enough current' to please the MA rx6, apparently. I quickly gave up on the speaker.
In home demo, the arcam a28 took the edge off the ma rx6s brightness for me. A lot of people find it very refined and polite. Rude people called it boring. 🙂
Don't even think of going the Naim route.
Nad 356 might have enough power, and if you're in the US/Canada, it'll be a good deal too.