Having had installed the JCAT XE USB, thought I'd share my thoughts on the difference over the stock USB port off an Aorus Z390 I Pro Wifi.
To briefly summarise, the most notable changes would be the sense of pace, the void that allows for perceiving spatial volume, the resolving power, and volume dynamics.
Pace, sense of rhythm, what makes you innately wish to tap your feet to the song - not something I was expecting as an improvement, yet one of the most notable pleasures I had to gain from this card. A singer's intentional pause/hesitancy to a phrase, to progress the story of a piece of music, the clarity of a drummer's timing changes, the change in pace of the song - the XE seems to manage to stretch these transient events out and allow one to enjoy the moment for longer.
Space, a sense of instrument separation, staging/imaging clarity - this is usually the easy thing to discuss and determine. But this might be the first time I've so clearly noticed the volumetric sensation of a high hat - from the clear crisp location of the drummer's stick hitting the metal, to the sense of the air surrounding the high hat itself, AND the wave of sound/vibrations as it travels from the point of impact outwards over the high hat disc. Or the spacing between the guitar strings as they are each strummed.
Yet this sensation doesn't come with the often felt "cut off"/stark isolation between the instruments, one can still perceive the "lack of sound" that identifies the space between the instruments, and that which gives an instrument a sense of volume.
Resolution, clarity of detail, transparency - much improved over stock. Bass depth, rapidity of impact (not hard over controlled, it still maintains the appropriate vibration/reverberations associated with each instrument), minute harmonics in cymbals, the clarity of the reed of a saxophone itself as it vibrates). Definitely found details I've never heard before in scores I've listened to for over a decade - the quietest of slithering of a drumming brush over a cymbal as the song fades out.
The sense of volume contrast was significantly better - at a macro scale with quiet lulls being dead silent (but not empty), but also with micro dynamic transients such as volume based vibrato of a singer/violin.
Sometimes, when a sonic improvement provides more detail, better control, improved bass impacts, you tend to lose musicality - the sound becomes more clinical, lacking expression. This was a concern as I read the reviews regarding the JCAT XE USB thus far. I think it has avoided that stigma, if anything improved on it in my month after installing the card.
I'm sure many have mentioned that this card removes the "digitised" sound/harshness commonly associated with PC sound sources - definitely my experience as well. Might be the reason I feel significant reduction in fatigue listening to the system after installing the card.
Additionally, I wouldn't say that the card has changed the tonal balance of the sound much at all, merely that it has brought what was there into focus.
Hardware:
Streacom FC5
G5400
Aorus Z390 I Pro Wifi
Corsair 2400 8gb
NJ450-SXL
SX8200 Pro (OS drive)
970EVO (Music drive)
Linkup PCIE Gen 4 Riser
JCAT USB XE
+ Lots and lots of software tweaking 
+ DACport LX
Notably needing to be mentioned - it was most unfortunate that the first card I received was damaged in shipping (and I'm most torn to see anything this refined being harmed), much to Marcin's acclaim he sent a replacement based only on a few photos!
Needless to say but definitely owed - thank you for conceiving and creating this piece of musical art Marcin.
And yes - usual disclaimer for the doubtful.
- I'm definitely too poor to chase audiophile "snake oil", the rest of my gear can be testament to that.
- This is an independent review, not sponsored, bought under my own motive and expense etc etc.
