Bill-p was kind enough to send some headphones my way. This first round included his modded LCD-2, modded MDR-Z7, and modded ATH-ES10.

Keep in mind how I hear things and my personal tastes with recent headphone impressions and measurements when looking at everything below. If you don't normally hear things the way I do, take this all with a grain of salt. We all have physical differences that play a role in hearing, various tastes, different gear, different music collections, and so on. So don't get hung up on anything you disagree with. For a quick reference and reminder on what I think of some popular headphones:

HD600 - Very nice, mostly neutral, but a bit hot in the 2-4KHz range for me depending on material and how long and loud I'm listening. I find that boost in the 100Hz area to be somewhat favorable, but could use more low-bass slam and power.
HD650 - A bit bassier than the HD600 (but with less THD on my pair, so can be cleaner sounding) and with less of the 2-4KHz bump, but largely similar, at least with the pair I got. Upper treble seems a bit sharper and grainier than HD600, somehow, despite being pushed down more in comparison. Don't ask me to explain why, cause I dunno.
HE-560 - Nooope. No way. I've heard two recent pairs now, and the emphasis in that 3-5KHz range just kills me. Like sticking nails in my ear. Certain mods change it from nail to icicles being stuck in my ear (so, a bit better). Treble beyond that is also too elevated for me. I found it so uncomfortable to listen to that I really had a hard time picking up the otherwise good qualities of the headphone. Can't speak for possible product variation.
PM-2 (stock, not my modded one) - Good bass and mids, though a bit soft sounding. On the slower and warmer side of things. Upper-mids and treble as a whole are depressed and not particularly well integrated with stock pads. Some sort of weird treble spike that makes them sound rough and weird despite even the spike being pushed down.
Slants - Smooth and relatively fatigue free. Surprisingly good soundstage. A bit thicker sounding than I'd like (in the upper-bass and low-mids), but not too bad once you get used to it. Pulls details out better than you'd expect despite this thickness. A good T50RP mod but tone isn't 100% to my tastes. I enjoy it for the smooth, easy going nature.
PM-3 - Fun bass, but a bit too much for critical listening. At least it's not too thick or muddy and is better than the soft nature of the PM-1 and 2. Treble has a bit of brightness to it in some spots but is relatively smooth and generally pleasing to listen to. Faster and probably more resolving than PM1 and 2.

Now, with that said...First up are some thoughts and a really quick measurement take of Bill-p's modded LCD-2. Just the left channel, just one quick take. Doing my normal routine on these will be difficult anyway since the pads are angled and glued into place. I listened to these briefly, took some notes, and then snagged a peek at measurements (I never take measurements without listening first).

Modded LCD-2 Impressions
- Good bass and mids. Good presence and body, but not too thick. Nice sense of power and impact. However, a bit on the slow side of things indeed. Seems to get in the way of itself with some bass details. But really not all that bad, IMO. Very close.
- Somewhere there seems to be a suck out in the mids or some sort of poor integration from bass to treble. Something about the integration and cohesiveness across the spectrum is just off.
- Trebl e is rather bright and splashy sounding. Metallic. Makes the headphone sound really thin despite having thickness at the same time. Fairly clean, just oddly elevated. Kind of nasally. Weird timbre and tone. Hard to listen to for very long.
- Sounds like a U-shaped sound signature with perhaps more treble than bass.
- Despite bass slowness and an in-your-face, close sound (more on that in a sec), decently sharp and resolving sounding.
- Male vocals sound really thin and pushed back too far in the stage. Which is weird since the bass and mids are good. I think it's the treble weirdness that is doing this.
- Not very airy. Soundstage is more on the claustrophobic side of things. Not much width, or depth (if anything, more height than either of these). Layering suffers as such. Still decently resolving and doesn't get in the way of itself too much outside of bass, but just sounds like everything is way too close, in your face, and just too enveloping. Very "big" sounding but way too close and up-front about it.
- These actually kind of remind me of the HE-560, so it's not too surprising to say I'm not a fan of this LCD-2 mod. This LCD-2 mod does sound a bit smoother and easier to listen to. Less harsh than the HE-560, but brighter and more splashy, if that makes sense. More metallic sounding.
- I have never heard a stock or any other LCD-2 besides this. Or, rather, anything from Audeze.

I think measurements are quite enlightening in terms of how I hear these. Excellent response up to about 2KHz with a bit of a warmer, bassier tilt. This I really dig. Upper mids and treble is not only too emphasized after that but jumps up suddenly and sounds poorly integrated as such. IGNORE the THD below 100Hz. My heater is running and puts in those distortion artifacts, plus my setup is most limited with low-end THD results. THD as a whole starts to max out what my system can measure.

CSD is actually quite clean for this sort of response. Good job on that.

Dropped in a quick measurement take of a mostly-stock HE-560 as well for comparison (it was missing the ear pad liner vs stock is all). Sorry that the scales aren't perfectly matched up.