Latest iteration of my desktop mini-system setup.
We have:-
1. firestone audio 'cute beyond' class-A headphone amp (from taiwan, very nice little amp)
About 3-4 weeks ago I received the Firestone Audio "Cute Beyond" and the "Fubar III" product samples to review, courtesy of head-fi user miziq and Welcome to Miniature Audio -Firestone Audio -USB DACS -Headphone Amps - but I didn't have time to start reviewing them until last week. These are...
www.head-fi.org
Mine is quite an old one, they have updated the latest version with an upgraded opamp and improved power connector. Mine still sounds very nice with original stock specification. The guys who run this small company have a sense of humor in their product names and case designs (I love calling a product "fubar III")!

2. custom 24V linear psu for the cute beyond, this provided a big audible improvement in depth and resolution over a cheap switched mode, like the visual difference you get when putting your specs on. I don't have the test equipment to measure noise and ripple, however I can hear no audible noise with the volume on full and no music playing.
3. massdrop sennheiser HD6XX headphones; mine are the made in ireland version.
4. 4K portable monitor from aliexpress, mounted on cast aluminium (I think.. it's not plastic anyway) vesa mount swivel stand
5. lenovo KU-1255 thinkpad keyboard with matching mouse
6. Intel N100 mini pc hiding in the background; 16GB RAM and 2 TB nvme ssd
7. music playback using mpd
Very nice sound quality from this setup... it's 'almost hifi' using the onboard realtek ALC269VC dac.

It's quite surprising what sound quality you can get ouf of even a cheap onboard DAC. Using the onboard dac means no messing around with USB drivers. I guess something like one of the nice iFi dacs would be better though... if you can drive it.
I don't have bitperfect enabled, it sounds pretty good with the standard setup. I might experiement with bitperfect again some time.
Oh... and I'm running kde plasma 5 as the desktop (for hidpi support, for the 4K monitor). Browser is open on my favourite website.