Well, that's comparing an old DAC with something pretty new. The DAC1 is from like 2004-2005 and I never enjoyed my DAC1 when I had it. I found it overly detailed, verging on harsh with speakers (Dynaudio Contour S3.4) or headphones, even the HD650's. I prefer an articulate, yet warm and inviting sound.
I replaced the DAC1 at the time with an Electocompaniet ECD-1, which was much better. I'd say that using the ECD-1 with a nice headphone amp (my DIY PPA), the iDSD Micro with internal HPA is more detailed and refined, yet perhaps a tad less warm (This is also from memory...). I believe that while using the analog RCA outputs of the iDSD is a good experience, but it might not be as solid as with what my old ECD-1 would have provided. I believe the iDSD's strength really lies in using it as a headphone amp/DAC. Don't get me wrong, it is good, and the technology is state-of-the-art, I just mean to say that it may not stand up to a dedicated component DAC that has all the advantages of a great power supply and MUCH more PCB board space with discrete components instead of opamps as well as other luxuries that come along with having less design constraints.
Obviously the ECD-1 lacked a lot of features the iDSD has, so this is really an apples to oranges comparison. I sold the ECD-1 last year and was experimenting with DSD DACs and I also had, at a point for a few weeks, a TEAC UD-501. I was one of the first folks with it when it was released in the U.S. and was very excited to get it. I can definitely say that I like the iDSD more than the UD-501. At the time, the UD-501 was groundbreaking for offering DSD at such a low price point, but after living with it for a few weeks, I just didn't feel like it had any "magic." It dutifully completed its job, converting digital to analog, it served its purpose, but it did not evoke any emotions. I didn't feel inspired by it; I was not bathed...immersed...lost...in the music like when I experience a great component. It was simply the sound of my music being reproduced...if that makes sense. It did, however, sell me on DSD. I ended up selling it because I upgraded to the Meitner MA-1, which is amazing. It was made even more amazing by a firmware update last month that enhanced the digital filters in the Xilinx FPGA that powers its heart. The iDSD is no Meitner, but then again, it fits in the palm of my hand and is battery powered and it was $500.
So, in short, below is my opinion, comparing it against other DACs I have owned in the past. I believe it competes well considering its price. This is apples to oranges, so take it for what it's worth:
iDSD > Benchmark DAC1, yes hands down; I very much disliked my DAC1
iDSD > TEAC UD-501; I have had more fun in two nights with the iDSD than I did in weeks with the UD-501
iDSD > Electrocompaniet ECD-1 for headphones using the iDSD internal HPA, but the ECD-1 was more "enjoyable" through speakers
iDSD < Meitner MA-1; no contest in a desktop DAC scenario
Edited by RHMMMM - 8/17/14 at 7:37pm