i cannot comment on your setup, as i have no experience there.
but, regarding expensive amps/speakers; did you see the video where the designer of cube audio and qualio speakers says the fosi za3 (and the aiyima a07) are better driving his qualio iq speakers (€6,900.00), than the €4,500.00 naim integrated amp that he was using previously? in comparing the fosi za3 to the aiyima a07, he says the aiyima is a bit more open and dynamic, while the fosi has more "richness". and he mentions a uk buddy who prefers the aiyima a07 max amp to a €10,00.00+/- vitus audio integrated amp. he did not say which speakers he was using. (i suspect the cost is higher, as the least expensive integrated amp i see on the vitus website is €17,000.)
and, both per the youtube vid, and ungeduld's comments above, there may be slight differences between amps, and between amp/speaker synergy...
doug s.