I've been comparing the K712 PRO vs the modded Q701 (stock pads) for the last 2 hours. I took notes but I kept repeating the same things.
I honestly would probably fail a blind A/B test. When sitting there I often forget which headphone i'm listening to.
K712 has a little more body to the sound. A little warmer. Modded Q701 slightly thinner. On some recordings there is no change or it's difficult to hear. Vocals sounds really good on the K712. At random due to recording they can sound more forward on the K712.
You switch songs and often they're more distant! I think when a recording has a good soundstage specific vocals sound more accurate/spaced back. They'll only be like this if they're supposed to be that way in the recording. I love this.
Modded Q701 generally sounds a bit more spaced out with some recordings and more airy/open sounding. K712 probably sounds very slightly more closed in due to extra warmth. This makes sense!
The low mids of the modded Q701 sound more accurate, but some might prefer the minor difference on the K712.
Neither are very forgiving of harsh/bright material to me. K712 doesn't really sound any smoother to me. Sometimes it's easy to be fooled because of how the mids are fuller.
I get that with the HD-650 too.
On very warm or bassy material the K712 can sound more muffled or less clear. This is very rare and not very audible. I have a few examples..
Again..both are good and depends on preferences.
I probably won't be buying a K712. If I didn't have a Q701 or was too scared to mod it I'd maybe buy a K712.
Stock Q701 still sounds great as it is. K712 and modded Q701 are for those that want a little more bass and some more warmth.
To me the differences are less than the HD-580 vs HD-600. I had them both for years. Remember on those the grill causes the changes. A 5% difference is being generous.
EDIT: The K712 mids are kind of addicting. It's a good headphone for relaxing and often it fools your brain into thinking it's smoother, but it's really not. I get a similar impression when I made the mids of my DJ100 thicker/warmer with different pads (Auray Velour). The thicker sounding mids just seem to obscure extremely subtle detail I think. Not too badly. Perhaps the K712 is slightly more musical to some and it makes sense. A K712 PRO might be similar to like an HD-598 on steroids. A less forgiving one anyway.
K712 sounds best when you don't over-analyze it and just listen to relax, which is what I did on the first day. It really does sound like a mix of the K702 and HD-650.
After about a million tracks I finally found one where the K712 made it SEEM not so bad. It was a low quality recording that's basically tinny/harsh/bright noise from a Japanese singer named Hitomi. I'd say it's probably more easier on the ears with the K712. It sounds smoothed over a little and not due to less treble I think.
Edited by tdockweiler - 10/22/13 at 1:58pm