Gave it a try, there's a slight hiss, not obnoxious but noticeable, depends on what volume you listen at. I listen around volume 20/120 and it didn't bother me much, but again, noticeable under scrutiny. In terms of OI, I didn't find the effect to be huge compared to the Shanling M2X (same price, output impedance <1ohm single-ended). There definitely wasn't as much warmth in the low-end, delivering a slightly brighter sound than the Shanling. Again, the difference was not huge, as I used an in-line splitter, it was more apparent to me than would be under normal conditions. You will get pleasing results with the M9 but maybe 10% more balance out of a 1-ohm source (this is very subjective).
And just wanted to share my latest photoshoot haha, going against my usual work here, I try to match colour with monochrome, monochrome with colour, but I've just hulked out on this one. Whether you like the sound or not, we can all agree these are some iconic designs