Now at home after what listening i'm in doubt. Isn't the rx 6 the better speraker? Yes; the rx8 has more bass, that's what i like. But it seems that the balance of the rx6 is better. I'm going on with listening.
The quality bad? I have the NAD 355 and no problems at all. And I think you will upgrade in 2,3 years to spendor/naim maybe. I think you should just buy the cheaper MA/NAD and enjoy the music. Otherwise you spend lots of money on spendor/naim but maybe you don't like it.
The Reference 3.2's will walk all over the RX6's, but they need much better amplification than the MA's do. You'd have to be looking at integrated amplifiers of at least £2k, but ideally pre/powers to get from them what they're capable of. With the right amplification they'll reward you heavily, but this route won't be cheap.
It's better to have a lesser speaker driven properly than a better speaker not driven properly.