I just made a few tweaks that resulted in the sound from my week-and-a-half old HD580 to improve from sounding "really good" to "awe-inspiringly beautiful". The more the HD580 were breaking in, the more I was hearing "the veil", or really "the vale" in their high frequency response. At the same time, their decay was becoming so lovely.
The first tweak was to swap the stock power cord on the Behringer DEQ 2496 for a Volex shielded 14AWG power cord ($7 from Carlton-Bates). What was perceived by my ear as veil over (vale in) the sound is now GONE. The second tweak was to order the HD600 Decorative Grilles from Sennheiser ($10 per grille). In other words, inexpensive mods. Sennheiser had one grille in stock (which I have received and installed on the side of my dominant ear), and the other is expected to ship in 3-5 weeks (from Germany). This tweak has given the sound considerably more openness and cleanness of soundstage/imaging, and has resulted in a new level of clarity in the sound that has enabled another layer of good detail and subtletly to be revealed. That faint hint of interference from the intra-phone reverberation is so nicely relieved from the side with the HD600 grille (not so "one-sided" as may be thought - as the brain integrates the sound of both ears to produce an overall really nice sound). Can't wait for the second grille to arrive. The illusion that I am listening to sounds that are coming from the room around me and arriving at my ears (rather than listening to sounds being produced by mini-speakers at my ears) is appreciably enhanced.
A lot of what I LOVE to listen to is slow, melodic female vocal (Carla Werner, Heather Nova, Dot Allison, Emiliana Torrini, Delerium, Poe, k.d. lang, ...) much with electronica background. The HD580 are becoming THE can through which I listen to these. Their jaw-droppingly lovely decay is just to-die-for. For faster, more piercingly-edged sounds (The Crystal Method, Angelfish, Alannah Myles, ...) the SR225 is still my phone of choice. But, MAN, what a tremendously complementary set of phones the HD580 and SR225 are - to my ear, a much more complementary set than the SR225/K501. The HD580 and SR225 are so nicely complementary for a) the different sounds that each does exceptionally well (so that between them, the range of sounds handled beautifully is increased), and (less noted) b) the aspects of their sound that they have in common (so that in gaining the special benefit of one, not much of what is really liked about the other is lost in the switch). One such common aspect between the SR225 and HD580 is the sonic impact that each is capable of. HeadRoom's one-liner on the SR225 for a long time has been "eye-blinking impact". There are tracks that my ear is used to hearing through the SR225 that, when I listen to through the HD580, the impact of the instrumental attack can literally make my eyes blink. Folks may call the HD580 "laid back" because of its high frequency response, but in terms of being able to deliver "slap-in-the-face / thanks-I-needed-that" impact, the HD580 are by no means "laid back" - much to the delight of my ears. And sonic textures are palpable (from ears to chest) with both phones. Both phones also deliver crystal clarity (without the faintest hint of grain), a sound quality that my ear revels in. My ears really LOVE the HD580 for what it excels in. And, when my ears love it, I love it. It's easy to hear where all of the appreciation expressed in this thread comes from.
