Ok so I’ve done more testing this morning, proper critical A/B listening with multiple songs, and not just with Poweramp and FiiO Music but also with Audirvana and my desktop amp/dac, and not only with the FH5 but also HD800 and Auteur.
As it turns out there are several variables at play here, but the bottom line is this: there is little if any SQ differences between Poweramp and FiiO Music, once set up properly (no EQ).
To be sure, I used the HD800 as a baseline reference, because if any headphone will pick out the smallest SQ differences from a source, that would be it. I suspect Poweramp might be a hair warmer than FiiO in its default configuration, which makes music played through FiiO initially sound ever so slightly ‘clearer’, but this quickly dissipates the more you listen. It also has a lot to do with the actual song and recording quality, because slight imperfections in the recordings at certain FR might be easier to pick up with Poweramp than FiiO. This could be placebo or imagined, because on some takes it’s there and others not.
I used enough tracks and went back and forth enough times to pretty much exclude any obviously noticeable differences between Poweramp and FiiO. More impressively, the SQ difference between the M11 and my desktop setup is really not massive, certainly not as much as you’d think there’d be between a $1200 8W fully balanced R2R amp/dac and a $450 550mW dap! Of course the desktop is more refined and resolving, but only if you’re really listening for the details. That’s not a criticism of the desktop setup, which I love (it’s my endgame in fact) but rather an endorsement of the M11 and what it can do. Midrange my a**
Things get more complex with IEMs. I find the smallest changes, tips, insertion depth - all make much bigger differences to the sound than with full size headphones. The slight harshness/thinness I was picking up from the FH5 and the M11 - compared to what I remember with the M9 - has almost been completely reversed just by switching tips from Spiral Dots to Dekoni Bulletz. Almost immediately the sound was fuller, a touch warmer, and the sub bass was back in a big way. Perhaps the more neutral tuning of the M11 and the brighter profile of the Spiral Dots are too much of a good thing, and could also explain the differences I was hearing between Poweramp and FiiO.
It’s probably too soon to say for sure, but now that I’ve switched tips, I’m back to being completely satisfied with the FH5/M11/Poweramp combo, and have even disabled RE EQ for now as I don’t feel I need it to tame the slight harshness I was hearing in the upper mids with the FH5.
Hope this all helps someone somewhere.
PS. We’re on 72 pages and already dissecting specific SQ details and apps on a product that’s not even officially available in the West yet! I have a feeling the M11 is going to do big things once it’s widely available...