Just my 2 cents, the X3800H will do much better with DLBC, or even just Audyssey, than the AVM90, that’s based on measurements, AVM owners who only gi by their perceptions will obviously think the opposite is true. As to minidsp, I have had 3, now two 8 channel units, they are no substitue to the AVR’s subouts that are discrete, and the minidsp’s are limited to 2 V maximum unless yours has balanced outputs. With the mini, you would be doing double conversions, ie ADC and then DAC, not ideal….
The AVM90 costs a lot more, probably 7 times that of the x3800h on sale, that’s a tough one to justify for a lot of users who just want a good practical option to enjoy HT and music, but for a fan of expensive Anthem AVM, it can br. great choice.