I finally had some time to sit down and compare these with m desktop setup, and the results are shocking.
Let me start by saying that out of my desktop cans (Senn HD600, HD700, HD800, Beyer DT880) the oldest and cheapest HD600 are actually my favorite. They're not 'the best' of the bunch, that award would probably go to the HD800, but they're my favorite. They're not as refined as the other cans (except maybe the 650) but I really like their general disposition, very smooth yet engaging and with enough of the detail to suit me. The Beyers have a much better soundstage and the other 700 and 800 both have better clarity while the 650 has better bass, but none of those cans SOUND as good to me. I would like an upgrade to the 600 someday - really all I want is the overall sound signature of the 600 with the soundstage of the Beyer, that would be my ultimate headphone.
I say all that not because I think the PSB are it (because they're not), but rather to provide an overall idea of what I'm looking for and put the below into some context. And since the 600 are my favorite of the bunch, that's what I compared the PSB directly to. The PSB, like the 600, have an overall sound that I find very pleasing, yet they don't sound like the 600. Here are some impressions from my notes:
First, the 600s were tested on my main headphone rig (Mac running Amarra Hifi > Peachtree Dac-IT > Schiit Valhalla > HD600), I consider this setup (while not super high end) to be a fairly respectable system. The PSB were run in Active mode (meaning I used the built in amp) straight off a 7th ten iPod classic (that's it, no LOD or DAC, just straight off the iPod because that's why I purchased these). So the setups aren't exactly a fair comparison, but that's how each can is to be used so that how I did the comparison. Lossless files were used on both setups.
The Senns have adequate bass, actually I'd say they have very good bass and I've never felt it lacking. The PSB, however, kicks it up another notch. And I don't just mean that they have more bass (although they do), I mean that the overall bass response is more pleasing on the PSB. I don't find it boomy or bloated, these are not a 'bass' can ala the Beats or even the Polk UltraFocus 800, it's just a very natural sounding bas response. One of my favorite tests is about 3 minutes into the track Why So Serious from TDK score, and these passed even that with flying colors. The PSB are the best headphones I've ever heard at reproducing bass faithfully.
Mids and Highs
I don't know if there is a FR curve for these posted somewhere online, but if there is I'd guess it's relatively flat (with maybe a small hump in the bass to create what Barton calls the 'room feel'). These just sound very smooth and still accurate and detailed enough in the miss and highs. it's hard for me to describe the sound as anything other than damn near perfect. These headphones are not going to be the final word on detail, but they're not far off. I get more detail out of the 600, but not ALOT. One thing the 600 does well is make lesser recordings tolerable to listen to, since they're not the final word in clarity either they ten to smooth over some of the edges on bad recordings, and this is one of the reasons I like them so much. The PSB are even better at that. Muse is actually listenable on the PSB nd on the 600 it's borderline tolerable depending on which album. I
The PSB are a closed design, but they sound bigger and less 'in your head' than any other closed design I've tried (I don't count Denon because they don't seal for sh!t). They have a surprisingly large soundstage and open sound for closed headphones, but that being said they still give up ground here to even the 600 which I already content lack a good soundstage. This particularly affects me because I listen to a lot of classical and orchestral movie scores and those types of music benefit from a more open sound. So the soundstage isn't the strong suit of the PSB, but it's quite acceptable and I go so far as to call it very good. Although not 'great' in the grand scheme of headphones, it's very good for this type of headphone. The closed design gives the PSBs greater impact, but you lose some of the air. Playing the two side by side it's obvious, but when I'm out and about with the PSB I don't feel like I'm missing much.
If there were a line in the center of the universe that designated a purely neutral sound, these would be just a tad to the right but they are by no means bright or overly forward sounding.
Overall my desktop rig is better and sounds better, but only marginally better on most material and actually worse on some material. So the desktop rig isn't going anywhere, but the PSB performs MUCH better than I though it would in comparison.
I honestly don't know why this headphone isn't a bigger deal.