I owned and loved the Audience Frontrow USB, but didn't care for the Studio One as much in my system.
Two recent finds that I enjoy more than the Frontrow are the Veritas Audax and the Tiglon TPL2000U.
The Veritas seems popular, I learned about it from someone around here and it is a great value at $450.
Tiglon is a brand that is new to me but I am really loving what I hear. Started with their Ethernet cable and enjoyed it enough to buy the USB. At $800 it is more expensive than the Veritas but arguably better in some ways. But I use them in different systems and I haven't compared directly.

