Hey Pedro, still rocking the HD25s, don't blame you, it will be difficult to get something with their kind of slam, in large part due tot he HD25's high SPL, closed cup design, and tuning. The can is legendary, and only held back the technical department a bit by a pretty standard driver.
As far as slam goes, I can only really talk about the HD650, which given its modest low-range frequency hump, is quite tactile with electronic music. Like the HD25, the HD650 does something with music that is hard to compete with - all the parts come together so well. It the frequency balance of the HD650 that allows you to turn it up a bit, and get a more visceral experience.
Now the low-end never hits the depths of the LCD2,and speaking of which, if I want real tactile slam the LCD2 outclasses the HD650 (no matter what the magic amp / cables/ etc) as its planar design extends low, with clarity, and lack of distortion. But the LCD2, isn't really a bassheads can, because it doesn't have that v-shape tuning, and even with EQ, it never has that bloom that a dynamic driver can give you which can be enjoyable.
I'd say both HD650 and LCD2 are on par though, for various reasons, even for listening to electronic music. Bass is only one aspect, and its arguable that the HD650 handles linear top-end frequency a bit smoother while being a more comfy.
The HD660S may not be a massive improvement, and does come with a price tag, but I will say that 150ohm power rating (like the HD700) really goes a way to helping these headphones become a lot more manageable from say an iPhone or portable. After recabling the HD700, they have a perfect balance between getting enjoyment out of a desktop amp/dac or just on the go.
HD700 - yes, technically the bass on the 700 is tighter than the 650. I feel it quite well-balanced, and in some sense it is like the HD25, as that bass actually isn't overly pronounced. I feel the HD650 and LCD2 will bring more 'weight' to electronic music, but the HD700 will soar with more experimental, acoustic-orientated electronic music, or very technical productions even psy-trance, IDM, etc. It's just another flavor really, but for the most part I'm going to reach for my LCD2 or even more so my Denon AH-D2000 / MDR-7520.
Which brings me to closed-cans in a way that
@DoctaCosmos discussed earlier (welcome back by the way!). A closed-can is going to bring a different level of engagement and 'slam' than opens do. The MDR-7520 out of all my cans is the one that can punch, not the lowest, but is intentionally designed to analyze music, including the low-end. Not too far off the design of the HD25, the 7520, also a professional headphone, is more spacious in size and sound. The dynamic driver in the 7520 is one of Sony's better designs and extends low/high. It's more of a HD25 replacement (though it is expensive) - but I'll tell you I still miss the HD25 (gave it to my brother)/
The Denon AH-D2000, however can be the most enjoyable with electronic music out of all of them. Unlike later design revisions of the Foster bio-cellulose driver, the D2000 is tuned flat with a bit of v-shape going on. Bass is delicious without being overpowered. One thing I've found out, is that the pads make a massive difference with these cans. I now have two D2000s, one has some older pads that are supple and with less width. They are the most comfortable and somehow the sound is just a step up compared to the other one, whose pads are stiffer and thicker. I imagine the sound of the newer one will change as it breaks in, just something to be aware of. This impacts most headphones even the HD650 series. The HD25/7520 don't have to worry about this as much due to their design (as long as you get a good seal and aren't using foam pads).
Not sure how much an improvement the 660S will be over the 650/600/580. If slams was a prime consideration it would be tough choice between this and the new LCD2C (a revision of the classic) at its $599 price point but I'd probably go with the latter.
