I picked up an Apogee Duet last Friday. I'm in the process of playing around with the various computer fed DAC options. I have a new Music Streamer II+, Centrance Dacport and an Apogee Duet.
I really like the Centrance Dacport for headphone listening. I have tried it, as suggested by Centrance, with the volume all the way up feeding a preamp. I actually like the results.
I have the Music Streamer II+ breaking in at the moment.
I was immediately impressed with the results I'm getting from the Apogee Duet. It really sounds great for both headphones and as a preamp/DAC option. You can also set it to "fixed output" mode, which sets the volume at a fixed level of 0, for intended use of a standalone DAC. I know it is early in the break in for the Music Streamer, but so far I favor the Apogee over the Music Streamer and Centrance.
I believe all of the computer fed DACs reviewed in Stereophile are USB DACS. Is there an inherent advantage to the firewire interface vs. USB? I'm using a MAC Mini as a server. I understand that USB is "universal" to both PCs and MAC, but I'm wondering whether the impressive performance of the Duet is solely related to Apogee's equipment, or partially related to the Firewire interface.