So the A80 is excellent for sound but I've observed some quirks that scratch the wrong bits of my mind which has meant I've filed a returns
1: When the display is set to anything but max brightness or off then a very low high frequency whine can be heard from the regulator I assume if I turn my head a certain way. I initially thought it was the power adapter but turns out that this is not the case. It's the same sort of whine you hear from RGB keyboards or mice when lowering the brightness which puts a load on the capacitors or resistors inside causing the whine.
2: When playing content like YouTube, skipping back and forward creates a 1s gap in audio before audio continues playing, like I can see someone talking, press back arrow to rewind a few seconds but it takes another second for the speaking to be heard like as if th A80 has to buffer the audio for resuming. Slight annoyance that.
3: The heat it generates is quite insane. I m assured 49 degrees on the housing exterior so the internal temp is obviously much higher.
Did a lot of additional research last night and ended up ordering th Fosi Audio BT20A Pro, it took has swappable opamps and iv already got the higher power adapter to drive to max capability. It's a simpler pure unit that has reviewed really well so am looking forward to feeding it via the K11 R2R using line out effectively as a pre amp which means saving a USB port from the PC.
This is fine by me as the R2R can function as line level out or volume controlled like out as well so depending on which I want to use as master volume, the option is there and the R2R DAC stage is excellent quality so no concerns there.
Shame as I really like the VU meter on the A80! Though ty Fosi is much cheeper and reads like it sounds better too with its transparency and simple approach.
Edit*
So I never actually tried the stock OpAmps with the A80, had the OPA828 in there from day 1 so figured I'd give them a try this evening and man, the audio quirks mentioned above are gone, it's smooth and warm with a near analogue sound signature like what I'm used to from past amps. I guess the OPA828 I had in there either aren't a great pairing with this amp or the chips are not genuine OPA828s given they were from AliExpress - The stock OpAmps are genuine
It's also not getting as hot any more, I reckon the 828s I have are either bugged or just not well suited to this amp. Guess I am keeping the A80 after all
The sound with the stock OpAmps is stunning.