But then you're stuck with Creative drivers. Nope. I've had Creative cards. Never again.
I've had the original STX for about 6 years. I also have an Mayflower O2/ODAC Rev. B. The headphone amp on the STX is every bit as good and is actually more powerful than the O2. It's just a little bright vs the true neutrality of the O2. It's certainly 'audiophile' grade.