New Firmware 10.1.0

[yabaVR]

Crystal clear and all the life and warmth is gone. Same deal as with the last few firmwares.
Fatigue within a few minutes playing some edgy tracks that I tolerate with fw 7.1.3.
Back to 7.1.3!!

I agree. I really like 7.1.3 but use 8.1 so I can use SAM which has clear benefits in my system.  I have tried all the subsequent FW releases and find them too bright with over-emphasised treble which increases the sense of airiness and apparent detail but makes recording hiss intrusive and increases listening fatigue. I also find the later releases less warm.

Seems like FW preferences are still system-dependent, which I don't find particularly surprising.

Hey Philip,
the recording hiss you mentioned actually is (in most cases of good recordings) out of phase audio signal informations (or simply put jitter) induced into the audio signal at some section of your system. I read in your signature that you are streaming from a MacBook. Unfortunately I'm not familiar with tuning software for Apple but what I can say about my journey on the PC side is that I was unhappy to stream from a PC until I tried some special tuning software like 'Audiophile Optimizer', 'jPlay' and the like to cut down all unnessesary processes that're running in the background of the OS. This, and only this, lowered the jitter of my PC as my source to a minimum level so that it is now pure bliss for me to listen to it.

Beforehand I couldn't get rid of the underlying digital sound pattern in the music and it's my thinking that you're hearing this digital sound pattern originating from your MacBook to a larger extension with the newer firmware versions. I also read somewhere that Apple OS have even more processes/services running in background than Windows...so that could make sense.
Downside to intensively tuning the PC is that it's now solely dedicated to audio, but if I look at it like a CD-Player it is a bargain for an audio source. If you can ever make it to get hands on a highly tuned audio PC it could be worth to install AIR on it and give it a try in your system.

I can say from my tuning experience that it is not more brightness or over-emphasised treble the new firmware produces rather than very high resolution of details and this results in more 'audio informations/time frame' that is then messed up by jitter patterns leading to more hiss and digital sounding. Increased Resolution of the signal is, in my thinking, nothing more than just more micro details that now come thru that were blocked on the signal path before. More signal informations equals more energy coming thru equals more level (higher dynamics) on particular frequencies/time frame equals hiss and over-emphasise when impured with jitter. Just my 2cents.

gui