I have both the AD700 and AKG Q701. For what it's worth, I'd like to chime in on just the headphone aspect. Hope this effort is interesting, and not a TL;DR :/
I have had the AD700 for a couple years now, and IMO I still think it is a great value headphone. A warm signature is mostly traded for an expansive soundstage... and I experienced a very appreciable difference between the experience in contrast to any other headphone I had heard until recently. The sound is very controlled and feels fast, pure, layered, and airy; combined with the massive amount of detail retrieval, I think the AD700 is an example of what can be achieved when the focus is on the mid/treble range and an open headphone, regardless of price.
Now, a conversation about bass. Some people talk about bass on these headphones like it suddenly stops making sound below 100 Hz. Obviously that is an exaggeration, the AD700 produces the low notes in songs like the beginning of Massive Attack's "Angel" that actually seems like a silent passage on earbuds. Bass IS presented on the dry side, you lose some of the sense of "body" and weightiness of the sound, but I think it's part of a trade off to keep the bass as tight and detailed as the rest of the freq range. Muse's "Undisclosed Desires" benefits from this presentation IMO, with a texture to the low notes that I find addictive and exciting in a different way from, say, on my near-opposite emphasis V-MODA LP. Also, while gaming, sometimes the rumble of bass gets fatiguing in long sessions, and as Mad points out in his thread sometimes the bass can distract you from detail whoring to the level of an imba advantage.
Mids, treble, and detail are really important for being "in the zone" when gaming competitively, IMO. And the AD700 does this really well. When playing CoD4 for some serious FPS gaming, it doesn't sound like real guns are cracking and grenades are exploding next to you... it's better. Not only do I not play at the deafening volumes of real life, but the tactical cues are a lot more intuitively grasped with the AD700 than with my different speakers and headphones. It really is a revelation compared to other sub-$100 headphones I have heard. I haven't heard a turtle beach headphone that I didn't absolutely hate by comparison. While some headphones go most of the way, the AD700 just does it with more grace, soundstage depth, layering and separation, and detail. I feel like that's 'nuff said describing it, but IMO mids, highs, detail, and soundstage are their own aspects of fun, and bass body is one more aspect.
I have heard a few headphones that challenge the AD700, and a few trade some of the AD700's precision and strengths for a more balanced sound (like the surprisingly good JVC HA-RX900 when modified with dynamat resonance dampening & other small mods, though I think it would still be just average while gaming), but they usually felt cheaper in construction and less comfortable to me. Oh, and comfort was a big factor for me... sometimes I have worn the AD700 for 8 hour marathon sessions.
Now, in July, I bought Mad's Q701 from him. I'm currently amping them just from my Recon3D and/or little FiiO E5, but I have a VERY nice custom tube amp on the way (look for more on that in a few weeks!).
For $120 extra over the price I paid for the AD700, I feel like you can take about every aspect of the AD700, and make 5% changes... but they are very welcome changes. First, the look is still unique, but the color isn't as polarizing as the AD700 purple. The comfort is different: having my somewhat large ears free from touching anything is quite nice, the headband takes a bit more of the weight and feels more traditional, but my thinning hair means the headband bumps bug me from "not even noticing it's there." I think my scalp is more sensitive than my ears to pressure, but the Q701 is slightly better at dissipating heat. Interchangeable cords inspire confidence, but the short cord is about the same length as the AD700: too long most of the time.
The sound: the main thing, it seems to have all the good points of the AD700, but with more body and noticeably less bass roll-off. It seems like the highs are ever so slightly smoother and liquid too... but within that 5% change. Now, there have definitely been moments with the AD700 where some sound in the background of a game or song makes me jump and look behind me for the source or check the window to see if it started raining, but overall the Q701 sounds more natural, and more musical, while still unveiling very fine details and nuances. The AD700 elicited joy and elation, the AKG Q701 still has that soaring joy but adds the authority and weight that leaves me blown away. The 5% change makes a % difference that I can't quantify objectively, just that, instinctively, I feel like I can live with this headphone and be done.
So, which would I recommend? I'm honestly not sure ;P
I don't think I could justify the cost of the Q701 back when I bought the AD700, and sometimes I still wonder if the differences are worth the cost, especially since money has barely become less tight since then and I feel like I need a better amp to fully saturate the dynamics of the Q701. I feel like the AD700 is great for gamers and good for music with one weakness (and it responds pretty well to a light EQ), and a good way to learn what most of hi-fi is about at a good price, but honestly it has had zero head-time since the Q701 arrived. Even with the lowly FiiO E5, there is a clear advantage in favor of the Q701. I am interested in comparing them again when connected to a high-quality headphone amp, but as long as I can afford the Q701, it has replaced the AD700 for me.
Edited by Evshrug - 10/3/12 at 11:01am