i agree with PurpleAngle if you dont like creative get an ST or stx (ST is supposedly a little better.)
BUT because the HD598 is relatively low impedance you will experience colouration due to the output impedance mismatch. There are ways around this like building a faux impedance decreasing adapter, but I doubt you will notice a difference. If you want to change the way it sounds you can always change the opamps.
And on a side note there are third party drivers available for the ASUS stuff. They are called the uni drivers.