I've basically decided tonight that the K712 are "it" for me.
My recent experience with the very good and comfy Beyerdynamic DT880 was very smooth and refined, but ultimately, compared to the K712, it was somehow both dull AND fatiguing. Tonight was my last shot, because I used my favorite tube in my great tube amp with my schiit Bifrost Uber... it helped things a little, but I still was disappointed. Bumping up the mids and cutting the treble at 8-9kHz by -3dB brought back energy and immediacy, spared me from the clean but piercing treble spike, yet also introduced grain and some distortion. Going back to flat EQ just sounded like a tinny headphone with good bass extension. This is after using them almost exclusively for about a week shy of my return period (so just over 3 weeks). The most fun I had with them was when I had them plugged straight into the little DSS unit, the 600 ohms made it fun to see how close to max volume I could turn the DSS (that unit has LOADS of volume headroom), and the DT880 were physically very nice comfort. However, soundstage and separation were better with AKG, the DT880 caused me a little struggle to hear right when enemies would appear around the corner but the K712 (especially when double amped... YEP) tapped right into my subconscious and it was like the walls were transparent.
You may be worried that the bass won't be strong enough for you to have "fun" sound, but I assure you that the K712 has elevated bass yet in balance with all else, you shouldn't struggle to hear low notes (like bass guitar) amid everything else. I'll even say that bass isn't the key to having fun... Some people chase bass forever because that's always lacking in earbuds, but you need the whole frequency spectrum (as well as resolution, soundstage, and "liquid" presentation) to really have music and audio key into your subconscious and unlock moments that feel like magic.
I have a test playlist of songs featuring different aspects of music that I had used over and over for years as my "standard for comparison," I usually listened for certain parts and then skipped to the next one. After 4 years and any headphone I bought or could borrow from a friend, these songs had become a bit stale. When I first got my Q701, it's funny reading my listening notes because I only got through like 3-4 songs before I just gave up on writing things down and just let the whole playlist play out.
I can't promise that it'll be to your taste, but it's a well-rounded headphone that is not a one-trick pony. More natural than HE-400, more detailed/resolving than DT880, more immersive than HD650, and dare I say more musical and less distracting (FWIR) than HD800. I haven't personally heard the top of the line Sennheisers, but I've read a wide breadth of reviews on them and many others, and no other headphone (besides maybe Etymotic ER4S custom earmold IEMs) is attractive to me right now. That said, I might trade my K712 for K702 Annie's for aesthetic reasons, lol, and the regular case 702 is probably a better bargain unless you really need that extra 3 dB bass.
Edited by Evshrug - 7/29/14 at 1:05am