Got all of Dekoni's HD6XX pads in for a comparison. Baseline is against my modded HD580 (red/orange line). For those who are wondering, I'd say it's basically a slightly brighter-sounding HD650. You can find instructions on how to mod your own in my thread in the modding section. All of the pads were measured with the following condition: stock HD580 w/ foam piece in the back (I re-inserted the foam piece for this comparison), absolutely nothing sitting in the front (so bare driver exposed). Why nothing in the front? You'll find out soon. Modded HD580 vs stock HD580 w/ Dekoni Velour ear pads: Quick sound impression: dark. Modded HD580 vs stock HD580 w/ Dekoni Leather ear pads: Quick sound impression: decent, kinda dark but still neutral-ish. Modded HD580 vs stock HD580 w/ Dekoni Hybrid ear pads: Quick sound impression: very dark but kinda shouty as well. Modded HD580 vs stock HD580 w/ Dekoni Fenestrated ear pads: Quick sound impression: decent, not dark, kinda smooth but sharp-ish sounding. I like leather and fenestrated the most. Leather is a bit more shouty than my mod, but it sounds very similar overall. Warm-ish tilt. Fenestrated is a bit of an interesting beast: it's a dark/smooth sound but it has a weird sharpening effect. I'm guessing this is because bass is not as crazy, and treble is fairly linear (in measurements at least), plus there really is nothing sitting on top of the driver this time so it has a bit of that "raw" sound. Would have been interesting if this was an HD600, because I get the feeling the HD600 would be almost neutral here. Anyway, I don't think any of the ear pads above will play well with HD650/HD6XX, sadly. They may be interesting on HD58X and HD660S, though, and I'm guessing Dekoni did their testing on those headphones (or one of the new HD600) rather than on the HD6XX. Trivial: all of the pads are very well-constructed. My old Senn ear pads are close to the end of their lives now and they look very sad. Will order new pads, which come with the stock foam piece, and then I'll do another set of measurements of these pads versus the stock headphone. Right now, these pads sit at over 2x the distance from driver compared to my poor ol' Senn pads. Will do photos/pics later when I'm less lazy and it's no longer night time.