I used to use only ALSA. Swiched to pulseaudio with alsa but avoiding resampling. I dont think that complicating stuff add any benefits… latency maybe and more processing for the audio. Let the dac/amp do the work

" Treble sounds kind of grainy,"

Perhaps Beyerdynamic DT 990 PRO will bring that extra brightness

r/headphonemods

r/diysound

Those unshielded “premium” audio cables make me cringe

Crinacle has frequenzy response graph comparison tool for headphones

https://crinacle.com/graphs/headphones/graphtool/

Rick and Morty (Rameses B ‘Psytrance’ Remix)

https://www.youtube.com/watch?v=iMHVfCyElW0

It would be best If you have a change to listen on them on the store before making decision

I would recommend the 560S over HD600 because hd 600 is a little darker compared to 560S. If its more bass that you are looking for then the HD 650 would be better option.