What is the best practice for people who use headphone amps side by side witih a usb audio interface, such as ---- http://www.amazon.com/American-Audio-Versa-Port-Soundcard/dp/B001N7QR6K/ref=sr_1_85?s=musical-instruments&ie=UTF8&qid=1300548899&sr=1-85.
Is this unusual at all or is there another solution for those who want to have incoming Vinyl, etc. as well as a headphone amp.
