Hi Pedro,
You've probably already heard my comments, but I thought I'd chime in again. I mean can you ever get enough of these headphone comparisons? I know how much you like your HD25, which is why I think I can bring some perspective, as I've owned the AH-D600 for quite some time.
I'm also right in the middle of a listening session with some of my headphones and a new dac/amp - JDS Labs C5D.
I think all of those are great selections. I had a chance to audition the P7 and I could tell it was quality. It seemed to be in the vein of the Momentum.
Recently I picked up a JDS Labs C5D to power my HD650s. I was hoping they'd make more of a difference with my other cans (HD-25, AH-D600, Amperior) but if there are differences, they are subjectively very minor compared to just powering those headphones directly out of the iPhone 4S. I imagine it
is better, and perhaps if I was to be able to properly ABX between them I'd tell. In my mind, I am think out of the C5D everything is just a touch clearer and more controlled. Still very respectable sound directly out of the iPhone 4s, so no worries not having a dedicated amp/dac for the HD25 or Ah-D600.
However, the C5D has brought the HD650s up to a level where I can say "okay this is what these headphones sound like and I absolutely love them". If they can get better through other sources, great, but right now they lead the pack of my headphones by a margin.
Its hard to place the AH-D600. They have their own character. They are very liquidy sounding to me. I'm immediately comparing them between the HD-25 right now out of the C5D. The C5D has a very cool bass emphasis feature. The D600 doesn't need it, but enabling it for the HD25 brings the low end much closer to the AH-D600. I imagine EQ would do something similar, but this is done right on the board itself, and is conveniently accessed via a switch. Seems like implementing this was not just for fun, but was engineered to be quite musical. The results are great (not that I'm necessarily recommending running out to get the JDS Labs C5D, because for its price you could get another headphone).
What it comes down to is the HD-25 is such a capable headphone, you may not
need to get another closed headphone - especially a closed headphone. I'm listening to them right now (Andrew Bayer - Let's Hear That B Section Again!) and they have practically vanished in listening to them. I almost forgot what headphone I was wearing (AH-D600 or HD650). I also have new aftermarket pads, nothing special, but they are quite soft.
Now switching back to the Ah-D600, yup its more refined, spacious and with detail. For this music its great, just a tad bloomy on the bass (turned off the bass boost of the C5D). On the same album Andrew Bayer - All This Will Happen Again, the pianos have just that much more separation, with quite a bit of weight to them.
Switching back to the HD25 confirms this. The instruments are more 'stuck' together. The piano less dynamic, especially on the lower registers.
Going back to the Ah-D600, you gain a greater sense of openess and air. I remember first listening to the D600 and thinking it was quite spacious sounding of many of the closed headphones I've listened to over the years.
Switching to rock music:
T Rex – The Wizard
Sparks – Who Don’t Like Kids
The Stranglers – School Mam
Bauhaus – King Volcano
Okay with the HD-25, yeah even a little bit of bass boost can help here. I'm fine either way, but it sure adds just that bit of energy to the percussion, guitar and bass. The C5D has 3 settings for the bass curve so quite useful. Switching back to the D600, its perhaps just a tad sharp on cymbals. T Rex sounds good, but I think overall I'm preferring the HD-25 for rock. Vocals and instruments just seem to be better balanced.
And for a real reference putting on the HD650s. Yeah, you'd love these
the HD25 would be closer in presentation. Really good. The 650 have even better balance.
And confirming this, switch back to the HD25, more recessed in the lower range, add a bit of bass boost from the C5d, and you know what, this is very very good sound. Closer to the 650s with that bass extension enabled. Anyhow, you can seriously enjoy any rock music with this headphone. Yes it may lose out on some air, but the presentation is so good. If this is Sennheisers 'Grado' then Grados must be quite good (never spent any serious time with them).
Okay so why do I like the Ah-D600? Well truth be told, I'm not sure I would have purchased them if I had my HD-25s at the time. But what got me interested in them?
Switching genres, lets put on some trance music, more in the vein of psytrance. Playing some tracks by Ritmo on the HD25. Wow, pretty awesome. Plenty of kick, especially with the C5D bass enabled. Pretty enjoyable.
Switching over to the D600, its definitely more visceral, with a whole level of sub-range bass added that just wasn't even there with the HD-25 no matter how much you boost the bass (you'd be just boosting mid-bass). So its quite full. The highs are a bit extended, almost sharp. The large bass and detailed highs can make the mid-range recess with the D600. But with a bit of acclimation, this is what these headphones do well.
back to the HD25s, and yes, just like other music, you notice everything just kinda of close in and squish together a bit. Balance is fine though, and again after listening for a bit you acclimate and enjoy the music. I'm enjoying doing this test, as its the first time I've been able to really compare these headphones, and with the C5D. I will be running the HD-25s with the C5Ds bass emphasis on, especially for electronic. It sounds that good.
Going back to the AH-D600, better but perhaps a bit hot on the highs. Not that bad though. Much more space though, you are at a party listening to these headphones.
And for reference over to the 650s who also can use the same level of bass boost as the Hd25. Its a more balanced sound than the D600 for certain, even wider soundstage but not by a huge margin, better transient detail in the mid-range, highs are better and there is plenty of kick, just not very low sub-bass, but better quality of bass than the Hd-25.
Back to the D600, and they are quite thunderous. See the thing is, you can't or should not be listening at high volumes for too long, as enjoyable as it can be. At lower and relaxed listening levels, where
Fletcher-Munson curves are quite different, the non-neutral v-shape signature of the D600 is actually of benefit. At lower levels, it actually is balanced, or creates the perception of balance as you can clearly hear both low and high end.
To further enable this advantage is that the D600 is closed, so again you can lower the volume and isolate better. It isolates quite well. I don't think you'll have the same problem you had with the 550s. The ear cups on the D600 shape around the ear. They mold to the head, whereas the 550s were more like saucer discs.
Switching back to the HD-25 on the lower volume, these are so good. A bit of low bass boost (depending on music) and it also works great.
Oh, one last test... time for some drum and bass (The Upbeats - Beyond Reality). HD25s again sounding awesome, with the bass boost on the C5D. Switching them to the C5D highest bass curve, is too much, like distorted mid-bass.
Going back to the D600, well, actually I thought there would be more of a difference in satisfaction. You immediately hear the change in balance, much brighter highs on the D600. Again, this helps with some detail too. Well there is a lot of difference, mainly that the D600 doesn't need an bass boost enabled, it has that character built-in. Definetely there is more air and depth.
So after all of that, again. With any of those headphones on your list, be it D600, NAD, or P7, they may be more refined in certain areas, have a larger soundstage, and be comfortable. But as far as enjoyment, the HD-25 is pretty high up there.
So if you really need the isolation of a closed headphone, something that is very comfy, would use it with both music and movies, would take advantage of its high-quality long cable and shorter iphone cable, and no dedicated amp requirements then the D600 is a good choice. Great for low-moderate volume listening, electronic, pop, acoustic and instrumental music. Maybe not the best with vocal orientated music. It has very good detail and technicalities, but its quite a different signature than the HD-25. Which to me is fine, why have two so similar closed headphones? Yes the HD-25 is very portable, but with the right pads and cables can also be your home closed set.
Ultimately if you are going to spend the money, get something that will compliment rather than replace the character of your HD25.
For comfort, detail, spaciousness, you can get an open headphone such as the Fidelio X1, HD558/598, etc.
I've owned all of these closed headphones - MRD-1r, MDR-V6, K271, SRH-840, MDR-V600, Koss TBSE, HD-280, Amperior. The HD-25 I've owned for years, with a bit of hiatus after lending them to a friend. I've heard nothing like them. Even the Amperior is quite different.
Enjoy your HD25.
