If I have understood MQA at all (which I may well not have done) it is primarily about maintaining the phase versus frequency integrity of the original master tape ('timing' in Meridian speak) by careful encoding and decoding.

Provided any subsequent signal treatment is good enough that it maintains that reassembled phase versus frequency linearity then I don't think such treatment destroys MQA.

Whether Meridian's A/D and D/A processing is that good I do not know, but it could be. It might no more destroy MQA than phase/frequency non-linearities in the (analogue) amplifier feeding your decoded MQA analogue signal to your loudspeakers.

Perhaps that is why M say that you need SE speakers and digital feed right through to those speakers to get the full MQA benefit: by that route they can tightly control phase/frequency non linearities right up to the moment of air being pushed, time aligned, by the loudspeaker 'cones' in the truly final step in the chain.

Cinema/Music: Trinnov Altitude32 8-16,218,Cloud 4 channel, Marantz UD5007,DSP5200SE(2+C),DSP3300(4),DSW(2),271,MShort Ceilings,AppleTV 4K
TV: Marantz SR7013 Wharfedale Diamond 9x4+Celestion(C)
Music: Roon,i7NUC8gen,QNAP TS253A, Sony Scala, MS200, Garrard DDQ650,Wharfedale Diamond 12.3
Kitchen: AD88 (bluetooth via i80).