When Quincy Jones produced Thriller, the studio had the best sound system the world could offer. Quincy said "now play it back on a pair of small speakers". When asked why, he stated that it had to sound good on them also. This was what most people would be listening with.
True, but the lower frequencies you can only check on a better class speaker set ...
I really liked my Soundblaster Audigy ZS2 with all the extras it had via the connected break out box. Headphones, SPDIF. Alas it had the old PCI slot connection, and of which my new ASUS board has none. It has 64bit windows drivers, only you cannot use the internal software and hardware chips for Soundblaster FX processing anymore, which i never did anyway, but the very good internal GM sounds and eventual soundfont import possibilities makes it a worthwhile system setup too for a stand alone dekstop PC. Far better than all the current mainboard Realtek HD audio chips everybody switches off in BIAS if they're serious about audio quality from a PC. -- My Soundblaster ZS2 set is still for sale BTW, as i was forced to change horses.
A difference you'll notice if the whole system is driven by a decent master wordclock like my RME UFX provides.
I noticed that after a change to a Yamaha 01v96i USB audio interface using it's own wordclock. The yamaha desk wordclock sync slaved to an RME sounded quite better. Good testers for digital sound quality are decent piano recordings or cymbals. -F