I received the Apogee today, as it turns out. Overall I think it is a very nice upgrade in terms of clarity and soundstaging depth, width and detail, but like the Apogee ONE, I am not that thrilled with the breakout cable. On the A/D side, the mic cable connectors have been improved greatly, but I am getting better results using a custom-made Cable Pro Panorama 1/4" stereo to RCA adapter cable through the Duet 2's headphone jack, and also by using my AudioQuest mini to RCA plug adapter with Cable Pro Dimension RCA cables through an additional cheap 1/4" to mini plug adapter when hooking the Duet 2 up to my speaker amplifier than by using mono RCA adapters put into the breakout cable going through the Dimension RCA cables to the amp. Additionally, I find that to get the most detail, I have to replace the stock USB cable that came with the Apogee Duet with a Kimber Kable USB CU B-Bus cable. Without the Kimber Kable usb cable, the sound of the Duet 2 is overly smooth, and fairly less detailed. However, the Duet with its' stock USB cable is more detailed than the ONE with a Kimber Kable USB cable. The ONE with its' stock USB cable sounds a bit congested in the midrange, which isn't the case with the stock cable on the Duet 2 (which is of a much higher quality than the rubbish cable that the ONE has).
So, when coupled with the Kimber USB cable, the Apogee Duet 2 not only is a very capable A/D D/A box, but is also a great headphone amp, driving my K701's with exceptional bass rhythm and clarity, along with very detailed mids and highs without the sterile feeling some amps and DAC's give me. With the HD580, the sound is also very detailed and the bass is very well controlled, yet still is detailed and warm in the highs and mids. The HD598 also sounds amazing out of the Duet 2, with better control in the bass than the ONE, and a similar clarity that I used to have to add a Corda Stepdance to the ONE to achieve with the HD598. The ONE could barely drive the K701 and was lacking in bass control with the HD580. My favorites with the Duet 2 have to be the K701 and the HD598's though, due to the extra clarity of the K701 and the great soundstaging and fuller bass of the HD598. If the HD580 were my main headphones, I would love them being powered out of the Duet 2.
Using the headphone jack as a preamp to my speaker rig, I also get great results with a nice three-dimensional soundstage and tons of clarity, detail and finesse. I have to say though, that I slightly prefer the Duet 2 being powered with the optional plug in supply (included in the box) especially with headphones, as it seems to give a little more clean gain to the headphone amp than what is achieved through bus power only. I'll have a more detailed review later on in another thread, but feel free to ask any questions about my setup or anything else about the Duet 2 or my testing methodologies. BTW, the stock USB cable is not horrible that comes with the unit, but the Kimber USB cable makes the extra detail shine through, so that is why I used it to review the unit (it is a $65 upgrade (2M version) that is well worth it in my opinion).
--Eric
