4.4.9-rt17 series

[Leonard]

Bigger sound stage is what I noticed too..

Do you mean airy and thin? As in perhaps more "treble energy"? If yes, that's what I find too. A lot of the music I was used to listening now sounds harsher for me too. But I reckon it's the recording itself (Still a guess at this stage, as I'm still testing).

With airy and thin I mean that the music lacks 'body and weight'. As if you can see right through the musicians. They are not actually there.
I cannot say the sound is too harsh in my setup. However as the mid-range is less apparent the high frequencies are more prominent. I assume this is actually because there is less noise. This may also be one of the reasons that sound stage got wider.
In the end I think the new kernel is an improvement in terms of sound stage and less noise. However I still have to work on how to get that nice mid-range back again.