I hate velour, gotta get that out of the way. Not sure why so many companies insist on velour as the material to use with pads. What I own:Beyer DT880s (balanced)Beyer/Drop 177x GoSenn 660SMeze 99 ClassicsAKG K371Audio technica 990zAudio technica 500xBlue LolaX2HRSource: Android runnin Viper 24bit/48khz through optical out to smsl m200 dac to smsl sp200 amp.I know, i know, why so many headphones...Soooooo I felt compelled to write this review because i bought these when the ball and chain gave me a $100 gift card and the price had dropped. I liked the X2HR but didn't love them; wasn't in that bass canon great soundstage camp everyone else was in. Don't get me wrong, they are very good but the sub bass roll off is so severe, I just can't get the sound I like out of them. Reading the reviews of the X3 was a mixed bag, mostly because everyone was comparing them to the X2; it seemed if you loved the X2 then there was no need for the X3 to exist. A quick tangent on pads; to my ears suede is the best pad on almost any headphone. It does darken the headphone a little for sure but suede also takes the shine of the top end, something headphones like the K371s and 99 classics need in my opinion as they can be very bright (same for the X3, with the stock pads). Suede also takes away some of the mid bass, turning the 99 classics in into some real closed back monsters. Also, if you own a pair of DT880s and are not using suede pads I don't know what you are doing with your life; the sub bass roll off completely disappears (not so with X2) without hampering the soundstage. Sheepskin is good too and my 2nd fav but doesnt lower the mid bass.Back to the X3s. My favorite headphones before these were the DT880s and 660s. The Senns were the king of fidelity; if you wanted to hear the track exactly as intended, you wanted the 660s. Great mids and the artist is right there, great for vocals. The DT880 soundstage and imaging are superb; the stage isnt as wide as the X2 or even the 500x but you could hear everything. The presentation is as much about the instruments as it is the artist. The 177x are also superb for imaging but can get a little clampy after a while, and the bass, so much bass. I got the X3s 10 days ago...and haven't taken them off. Quick observations:Best looking headphones I have ever seen, period. Great construction and just a superb, understated design. They will meld into your desk as opposed to being an ornament.Most comfortable headphones I have ever owned, period. My first full day with them i wore them for 11 hours. You know they're there but after putting them on, I don't have to make any adjustments, they just sit there. I wear glasses, btw.Not sure why there are so many comparisons to the X2; while not a completely different sound there is a fullness to the X3 that I don't hear in the X2. The X3 can be driven off of anything to great affect; I also own a THX Onyx, HUD100 and ibasso DC03, all getting great volume and push right around 60% volume (sounds the best on optical, even at the lower bit depth).The most important thing: No bass roll off if you change the pads. The Beyers and ATs and Meze have moss bass, but none sound this good. No bleed, the drivers are in complete control on even the most bass heavy tracks (the X2s would distort pretty easily).Comparisons:660s The whole mix and incredible imaging. The mids are king here but if you want bass you can eq it in (if you change the pads) without distortion. Truly great headphones. The X3s are as resolving in my opinion but with a much, much wider stage (by design I believe the 660s is meant to be intimate). Voices are more full as well on the X3 and i would say the mids are just a good as the 660s.DT880 (250ohm) A lot more bass in the DT880 but the driver doesn't seem to be as fast; bass heavy tracks mask some parts of the mix when i listening to the DT880s while I still hear it all on the X3. You see a lot of headphones claim they go down to 5hz, i don't doubt it with the X3. The instruments are a little more lively on the DT880 but they are also closer to you; with the X3 those cymbals are waaaayyy over there (and I swear the bass is behind me), with the DT880, the cymbals are way over there. Not dissing the DT880s, those were my babies for a loooonngg time...but the reason I am writing this review is because they have been dethroned.Comfort, resolution, presentation, its like going from a Charger to an E Class; I loved my Charger but everything is just smoother in this E Class. I didn't buy these before now because i couldn't justify the price (didn't buy my 660s) but if i could have test driven before purchase, I would have paid the $350. The X3 does everything every other headphone in my collection does, better. One word of caution: aftermarket cords will not work with these headphones unless special ordered.4 stars is too few, the X2HR don't come close to these, not sure what people are hearing. I have the Dekoni choice leather and suede pads, both are more comfortable than the stock pads.5:stars is not enough, I have never had a better, more musical experience than with the X3s. Every genre, every type of song sound great, sound musical.Truly incredible headphones, buy them and don't look back.