Here are some kinda older first impressions I made jotted down a few hours after I got my iDSD up and running. It's basically a short comparison of the iDSD's amp section and my Cypher Lab Duet
darker treble and more laid-back
soundstage deeper but similar width
more mid bass body and thus more rumble
faster attack and decay and slightly thinner note presentation
better instrument separation
tighter bass and has a snappier punch
vocals are more forward
detail is more obvious
As a DAC/amp unit I've experienced more burn-in in device than I ever experienced in my headphones. I'm right now at 44 hours and it has improved quite considerably. Compared to my previous DACport LX and Duet, before any burn-in, the iDSD had an obviously wider soundstage but rather 2 dimensional compared to those two devices I find to be soundstage depth monsters. Bass was rather lean for me but deeper. It was more musical but imaging wasn't as precise. Over around a dozen hours it suddenly started sounding brighter and I was experiencing and bass was altogether lacking except in detail. Imaging also suddenly became more precise.
Right now at 44 hours (I leave it playing overnight). Soundstage depth is closer to my previous rig and there is more body to the sound similar to my earlier impressions but keeping the clarity that was gained earlier. Bass is much stronger, tighter, and deeper. It currently seems detached from the rest of the music as to not colour the midrange. It's rather hard to describe. All instruments seem more palpable like it's as if you can almost chew on them… I'd be quite happy if they stopped changing right now. The iDSD the best of musicality and the technicality is good enough that you'd never complain that it's lacking nor feel it to be intruding into enjoying your music.
I'm still deciding wether I should post a formal review after the 100 hour mark
On my Macbook Air (Mid 2011) and on USB power mode there is a slight hiss on BitPerfect when 3D is turned on. Putting it into "Standard" or "Minimum Phase" would remove the hiss again. 3D seems to only affect a small number of songs… mostly those with extremely different sounds coming out of the left and right channels. On other songs, there is a increase of soundstage depth and soundstage width but this is dependent on the track as well. Overall, the 3D is something that is rather hard to describe too as it seems to emphasize only certain higher frequencies yet is track dependent?? These higher frequencies include some hiss present already on the recording. At first I thought that even on battery mode the BitPerfect mode had hiss but then I realized even switching filters, as the 3D feature is part of the analog domain, there was no differences in noise between the digital settings. Lastly, the XBass feature is honestly subtle relative to the other bass booster features I've experienced beforehand. I actually prefer it this way but it will in no way fix bass-light headphones.
*huge huge development*
I'm noticing hiss (not from from the recording) from the iDSD while 3D is off, on battery mode, while BitPerfect. This is almost negligible as I didn't notice it at all up to now. It just so happens that it was a long silent passage in a song when I changed BitPerfect to Minimum Phase and poof, it's suddenly noise free with a black black background. This occurs both with the iDSD attached to my laptop or my phone. I find this quite disappointing as "BitPerfect" should be the best sounding setting. I doubt hose of you with an iUSBPower or a coaxial out will have these problems with "BitPerfect."
Interestingly enough, the free DSD tracks that I downloaded have no noise in any setting. I'm sure it's not already present hiss in the PCM files. Would anyone be experiencing the same thing? I prompt you to try picking a song with a quiet passage or a sparsely recorded PCM track and swapping BitPerfect to any of the other digital filter options even while on battery mode.
Edited by maricius - 8/16/14 at 12:32am