Thanks project86 for this detailled review. Especially for explaining some of the technical background and comparing to some competitors.
From the specs it should be possible to drive a 880 600 Ohm, we´ll see.
I did not expect that you don´t hear large difference using the psu or not. If this thing can be used on the road too - even better.
What you think about changing the OPA2227? Could be worth the try or wasting time?
I stumbled upon a thread here quoting a japanese site:
The stock MUSES8820 is a little boring (in their opinion) and the resolution merely adequate
MUSES02 lets the top end soar in comparison to the 8820, and tightens up the sound, but at the loss of some emotionality in the sound.
LME49860 is their top recommendation. Separation is good, and the sound becomes clear-cut/ 3 dimensional. Overall, clarity and detail are improved, without any feeling/impression of "edginess"
LME49720 is grainier than the 49860 and not worth buying over the 49860
OPA2134 is very energetic and lively, but because of this it may not suit all kinds of music
OPA2277 is more restrained than the 2134 but doesn't suit the AMP-HP very well
That was of course for the AMP-HP.
So if anybody has some free time and bucks - that´s a list of options to try.
And I would not necessarily think that 50$ is an obstacle as some buy RCA-Cables about that budget - and I trust more in the ability of an OPAmp to change interesting things than of an cable.