PhA,

Firstly welcome to the forum.

It is my understanding that 861v4 is the end of the line for your unit. No further upgrades possible. However this is still a great piece of kit especially with ID40 card.

MQA is 2 channel and as such your options are 808v6, 818v3 or the soon to be released 218. Sorry forgot Explorer 2.

My advice would be to hold fire until MQA availability and options become clearer.
There are many threads here to peruse for you to decide a direction for the future.

Hector

AV: Thorens TD160B, SME, ShureV15MK2, 500, 598, 861v4, DSP7200.1, DSP3300HC Samsung UE55, SkyHD.
DINING: MS600, AC200, DSP5200SEUG.
STUDY 504, Roon Nucleus + RevB, 808v6, 5200SE, Mac & PC (Touch Screen), Prime+PS Grado GS1000i
HORIZONTAL: M80, MS200, Red Rose Spirit + Sonus Faber Toys, iPad Mini
A capella to Zydeco