I know it sounds trite, but I've never heard a digital source sound so analogue.
Was waiting until USB was supported for KS and had to try it especially after seeing this comment
So, just did a quick listen and indeed: KS does sound very different from WASAPI.
In fact, differences are far from subtle: it's like KS seems to bring more light and seems to create illusion of more space by bringing music forward, closer to listener.
In contrast, WASAPI appears further out, darker...
Taken all together, WASAPI seems somehow detached, almost mechanically (maniacally?) precise where in contrast KS shines a warm, transparent, glow and seems a bit more personal, intimate or, simply,
softer ....
Difference is especially pronounced in higher frequencies, cymbals, high-hats or anything that makes sweeshy swooshy sounds - at least to me, KS makes them sound more 'sweet'...
Overall, difference between KS & WASAPI is not as big as, say, moving from foobar WASAPI to XX WASAPI which, in itself, is a huuuge structural leap, but is more like a change of character, a different personality: it's almost like Engine#4 is Engine #3's alter ego
Very, very interesting - it seems the choice between KS or WASAPI will depend on deep personal preferences or maybe even moods...
BTW Seems 504 still has some issues (after track has played in stealth mode I have to bring up GUI with Alt-X otherwise I get a bunch of 'No Track Given' or 'No permission to access <library folder>' messages, but nevermind, KS makes it worth a little trouble
)
Cheers,
Josef