I've been under the impression that the W series are more colored/euphonic, and the A series are less so since they're called "Art Monitoring" headphones, but PurpleAngel would know for sure.
W series are unique - it's hard to say "all W series are X" and have it be true, since each one is voiced differently (at least the few I've heard support that). W1000X are voiced in a more conventional "hi-fi" manner - they're somewhat v-shaped. The upper mids have a coloration which I'm assuming is a side-effect of their porting scheme - it can lead some things to sound a bit "nasal" or "honky" - it's quite nice with many vocalists and horns, but it can be somewhat odd with some electronic music. W1000X also aren't the fastest kid on the block, so while they're very smooth and airy sounding, they aren't speed monsters, which again can be quite nice with many vocalists, horns, jazz, etc but can come up wanting with some faster electronic music. W5000, by contrast, are a much leaner, brighter, more detailed presentation - they have forward upper-mids but (to my ears) its much less colored, the bass is much less impactful, and they're significantly faster - they lend themselves very well to pop, swing, big band, orchestral, choiral, etc and can do very well with some electronic music (e.g. trance, glitch, electronica, techno) but may not satisfy for bass-dominated genres like dubstep, hardstyle, happy hardcore, etc. From what I've read in professional reviews (e.g. Headfonia) and on Head-Fi, the A1000 and A2000 are reportedly closer to the W5000 or the AD series, in that they're lean, fast, and very detailed than they are to the slower and more romantic sounding W1000X, but I've not heard either of the A series. To my ears, the A900X is a fairly balanced sounding headphone, and I would regard the W1000X as a "bigger and better step up" as a result. While the W5000 are more detailed, faster, more spacious, etc their voicing is significantly different, so they're an upgrade in some ways, but a different path entirely in others.
I have an O2 amp and a Portable Fiio E07 DAC/AMP for when I travel. I gave the HD700s a listen today and they sounded pretty mediocre to my ears....so I'm thinking the W5000s, or the W1000s might be better options for me. I'm curious about what the differences between the W1000x and the W5000s are? Oh, and I noticed that I usually always love Audio Technica's headphones more than any other headphone manufacturer. As you can see, I don't have an extremely high-end setup, so maybe a more forgiving headphone would be better for me.
See reply above. As far as amplification I've heard neither of those amps, but neither the W1000X nor the W5000 are very hard to drive. The W5000 are more sensitive so if your amp is noisy or has tons of gain (or both) it may not be so fun, but from what I've read the O2 is supposed to be pretty dead silent, so it should probably pair well.
The HD 700 scales much better with higher end amps but yeah... it's not a headphone I can recommend easily. The W1000X and W5000 are completely different headphones, although I've never actually seen the two compared. However, the W1000Z (the W1000X's successor) is said to have pretty much the same frequency tuning as the famous W3000ANV. Below is a comparison of the W3000ANV vs W5000.
I've heard the same about the Z, but haven't heard them myself - the price will have to come down before I even consider them (and, if the last trillion AT headphones are any indication, the price *will* fall).
http://www.head-fi.org/t/634201/battle-of-the-flagships-58-headphones-compared#user_ATHW5000
http://www.head-fi.org/t/634201/battle-of-the-flagships-58-headphones-compared#user_ATHW3000ANV
For what it's worth, the W5000 is the lowest ranked headphone on his list, and he has absolute top notch gear so he's definitely driving them all to their full potential. He used an upgraded MSB Technology Diamond DAC IV, and various top notch amplifiers like the TTVJ Millett 307A and Woo Audio WA5 with upgraded tubes.
The more and more that advertising listicle is posted, the more and more I find myself really starting to hate it.
The W5000 (and the W1000X) aren't really that hard to drive - they're very sensitive and low impedance - so you don't need some magic amplifier or magic cable or magic [whatever] to "get their full potential." They'll play very nicely out of many devices, the bigger issue is the noise floor of many components will come through on the W5000 (they're quite sensitive), but this shouldn't be considered a universal problem for gear that specifically targets headphones. IME the bigger problem is if you're hooked up to something that has a stupendous amount of gain, which will give you almost no range on the volume controls.
That said, W5000 attract (I should say "attracted" - they're more or less unknown anymore) a degree of controversy and my theory (and this is not wholly original - I've seen this argument put forth many times in the past by people smarter than I) is that it ultimately comes down to (physical) fit and how you feel about bright cans. Grados are similarly polarizing, for largely those reasons as well. W5000 (and the 1000X to a lesser extent) do not fit as universally as something like the HD 600 or M50; their headband design is largely the culprit (it doesn't have as many axes of motion). They're also a bright and lean headphone, which won't play well with today's bass obsessed music and listeners. Even as a big fan of the W5000, I'll happily reach for my TH-900 when it comes to lots of contemporary music, and for me the biggest draw to them is their excellence with older music (e.g. big band and swing) and other content that's not as bass heavy. They're also fantastic when it comes to some electronic genres, like vocal trance, but again you can't expect a "pounding bass line." So while they're generally my favorite headphone, they're not my favorite headphone to suggest to other people - you should be well aware of what you're getting into, and specifically want something that's spacious, detailed, bright, lean, fast, sensitive, and has some coloration (specifically the forward upper-mids/lower-treble). W1000X, by contrast, are more "hi-fi" in their voicing, and lend themselves to a broader range of genres, but it's certainly more of a "jack of all trades master of none" situation. Both do very well with acoustic music, vocalists, strings, keys, brass, etc and will have more mixed results with electronic or synthesized music. If you're after absolute neutrality I would not consider either of them a good reference (instead look at HD 600, or better yet ESP/950), but for musical enjoyment they're both fantastic imho.
For some dramatically less biased, more detailed, and more comprehensive thoughts on the W5000 (some with comparisons) in the form of written-up reviews, give these a try:
http://www.6moons.com/audioreviews/audiotechnica2/5000.html
http://www.headfonia.com/wooden-kings-w1000x-w3000anv-and-w5000/ (they largely ignore the W1000X here, and while I mostly agree with Mike's reasoning behind it (he lays it all out in the intro), the flip side is that those shortcomings can become strengths with some genres)
http://www.head-fi.org/t/281593/the-showdown-grado-rs-1-vs-audio-technica-w5000-vs-sony-sa5000
http://www.head-fi.org/t/158031/review-audio-technica-ath-w5000-raffinato
I wouldn't say the W1kx and W5k are completely different. There are a lot of similarities particularly with regards to their generally brighter sound signature. The w1kx had slightly more punchier bass presence and could sound a little more balanced than the more leaner/airier sound of the W5k. However I didn't find the overall signature too different. If you like the signature of one, you will most likely agree with the other as well.
The main difference for me was that the w5k was less edgier in the treble than the w1kx. As a result you get more detail in that region, and I found it less fatiguing. I ended up selling the W1kx as I found myself reaching for the slightly more refined sound of the w5k more often.
The w5k has a slightly larger cup, along with more plush stock earpads that seal better and are more comfortable. There is a slightly larger sensation of 'headstage', though the w1kx is also open sounding.
I swapped out my W1kx pads to the W5000 - resulting in more comfort, and better seal (therefore better bass punch).
For another perspective, I found the w5k's mids and treble easier to enjoy than the beyer t1. I sold the latter as its treble peak seemed to overly mask over the details.
Most of the music I enjoy is classical chamber music (mostly string quartets at the moment) - I agree with obobskivich that the W5k does acoustic genres well, but so it the W1k. (Not necessarily accurately, but just lovely sound imo). The T1's lower bass extension however translated the bombastic grunt of symphonies more realistically than either of the two ATs.
One note of caution: you mentioned you enjoy EDM and alternative. I'm sure it's possible you could enjoy bassy music through the ATs but I wonder whether another headphone might be better suited. Both the AT woodies are closed so they will offer detailed punch or slam (partly through air pressure), compared to an open headphone, but you won't get a deep rumble you may desire from the ATs.
I agree with you.
WRT EDM and alternative, I enjoy the W5k with some electronic music very much, but other times I'm reaching for the TH-900 when I want some bass slam. W1kx are a bit more "down the center" in this regard - they have more bass, but its slower and less extended; I'd say they're probably easier to live with for a very broad range of genres if you put my feet to the fire, but ultimately I'm still likely to listen to dubstep, trap, hardstyle, etc on the TH-900 over either of the ATs. I like the W1kx most especially for slower music - like jazz, ballads, gospel, country, etc (and honestly would regard them as better here than either the W5k or TH-900 - this is where I'd disagree with Headfonia's interpretation of the W1kx's voicing; they're not necessarily worse, they're just doing something different).
