It is a valid question.

I recently had a very good demo of 818v2 into 861v6 (Thanks again Rob S!!). To my ears after many hours of listening I could NOT tell the difference between 818v2/ID41 and the 861v6/ID40 into 8k's.
I could switch between ID41 on CD and ID40 on AUX really easily and just could not hear a change.

Plugging the 818v2 into the 8k's clearly revealed a difference. It's a great unit. Details, punch, dynamics... everything.

So, I concluded that the 861v6 is the limiting factor here and even if the 818v2 is 110% SQ you will only get the 100% that the 861 can give. (made up % just to make the point.)

I chose not to get the 818 on this basis.

The 861v8 is another story. I feel that this is producing more like the 110% of the 818v2 and I have the added benefits of MRC, etc.

M suggested in Bristol that they aimed to close the gap in SQ on the 8xx range and I do feel they have largely achieved this.

In a raw shoot out the 818v2 may just edge the 861v8 BUT if you put the 818v2 through the 861v8 you are very likely to get the same SQ output.

That output is really spectacularly very good.

So, if you own both I wouldn't worry. If I was about to purchase then I would think twice.

This was just my finding. If a HH with both units working this way finds it different and can hear a difference when the ID41 comes from another unit into the 861v8 then that's great.

Interested to know what others have found.

Rgds,
Nick