Thank you. I haven't tried the K612 on my current system, I will be able to try it this weekend though. In the past I found the K612 had deeper reaching bass. But the K712s bass recently really came to life. The bass is a bit more textured than the K612 in my past experience but doesn't have the same linear nature, it does have a bit of a mid-bass emphasis to it.

great review kman! im getting the k7xx , just wondering what would be your ideal amp setup for these?

The AKG 712 has amazing synergy with the Leben CS300XS. I have tried my Fostex TH900 with the Leben & the match up is not steller. The TH900 is my favourite h/p.
I have tried the AKG with my Japanese Bakoon amp & they sound good - the TH900 is a much better match to the Bakon.
Kman you are right on the money in relation to the 712 h/p being amp picky - great review.

Nice write-up.

@toxicdrift Ideal amp, not really sure, it depends on the price and the tubes if it's a hybrid or tube amp. There are a lot of amps I haven't heard. But I do know they love a lot of current. 
 
@mrtim6 I would love to hear the Leben CS300XS sometime. But the price is way out of my reach. The K712 are truly picky, they are simply harder to make happy than my other headphones. Though I'm not sure if they are better than my HD 650 and DT 150 or not. That likely really comes down to the system which is better. Even on the Lyr 2 I can appreciate all three a lot.

Nice write-up. 
I have both the 712 and 7XX and I cannot pick them apart with the Schiit Vali. Both sound excellent. 

A good honest review, thanks It is appreciated.

Excellent review Sir!

I currently have a HD650 that I'm very partial too. Will the k712 be a good companion for Jazz or Orchestral stuff?

@Sennyboy

I'm very partial to the HD 650 myself, it and the K712 get about the same amount of use. The K712 is more dynamic and energetic than the HD 650 with a more spacious soundstage. The K712 has the upper hand for instrumental music, jazz, orchestral, and classical over the HD 650 imo. The K712 sounds good on those genres to my ears even on systems it doesn't really like. Where you run into issues with the K712 on systems with poor synergy and/or not enough power is mainly the vocals, particularly female.

Excellent review of the K712 Pro!

Excellent review!

If I were to use the upcoming Fiio X3K, will it yield better sound output on high gain, or pair an amp with the Fiio X3K line out?

@kman1211 Are the K712s similar enough sounding to the hd600s that it would be best to own just one? I have a pair of hd600s, and was wondering if that's the case, thanks in advance!

@Jeangenie  I feel the K712 is fairly similar to the HD 600 when it's properly driven, the K712 can be sharp in the treble, be a bit glary, and have some funkiness going on in the soundstage if they don't have good synergy. But I do find them to sound a bit different, the presentation is different and I find the HD 600 a little warmer and lusher with a bit of a softening effect on the sound compared to the K712. The K712 comes off as more nimble with similar warmth, dynamic, more spacious, and a bit tighter and more detailed overall. The HD 600 is more seductive sounding and the K712 is more analytical sounding. Both are what I consider very neutral sounding, just different flavors of neutral. Both can be very musical as well, but the K712's musicality all depends on the system, it can be boring on some systems. I do think in the end both are worth having. Especially if you prefer to focus mainly on neutral headphones and want different flavors of neutral. 

Very nice review. I consider it very accurate , almost 90% agreed, but the part on amp matching frustration part. I consider it a little bit exaggerated. 
I have both Sennheiser HD650 & AKG K712 Pro.

My Setup is a warm sounding DAC/AMP Pegasus II HP, It retails for 300$ and it's one of the best small combo you can find for the money, confirmed many times by direct comparing (A/B) to stuff like AudioGD NFB11.32 , Audinst HUD-MX2, Asus Essence ST + LittleDot MKIII amp etc).
Pegasus gives enough power for both cans. I use about 30% for HD650. AKG K712 requires more - about 50-55% of total amp resource. So yes, AKG is a power hungry headphone, but a 150$~200$ well match amp might be enough. I've also tested K712 on SMSL VMV VA-2 (160$), it has enough power and good synergy to handle the beast.
 
Ok, now the most interesting part :  So , which do I prefer more, HD650 or AKG 712, Will the K712 be a good companion for Jazz or Orchestral stuff ? To put is simple -> My HD650 went for sale. No place for a HD6** Sennheiser in my system any longer. AKG K712 is better in  most areas (faster, more life-like, more detailed, bigger soundstage, better tonality). Can't listen the "lazy" Senns any longer. Yes. K712 Pro are that good. From Power-Metal to Pop, from Classical Opera to HipHop, Sennheiser lose. 
In fact, AKG K712 are my new reference all-rounder. It's an end-game headphone for a person on budget. Combined with a high quality, worm sounding DAC/AMP (skip all Sabre32 stuff), this is the closest to perfection system, for less then 1000$. 
 
I tell you, guys, I'm not a beginner in this hobby, I am a classical guitar player, my wive is a composer. I had listened about 50+ sets of headphones, encluding HiFiman HE500, Bayerdynamic T1, AudioTechnica W3000ANV, AudioTechnica W1000x, Stax 4040 systems. 
My choice is AKG K712 ! I'll think of an upgrade (HD800 perhaps) only after I buy a bigger house, a car and fly to New Zealand. Until then, AKG K712 are my best (music) friend.

@kman1211 & @AlexRoma Thanks kman for a nice review and also thanks Alex for your impressions, I was truly wondering if owning an AKG headphone would be worth it. My only confusion with AKG is selection. It's getting hard to pick one but it sounds like the 712 Pro might be the ticket. My biggest problem at the moment is to find a top class headphone for classical music, I was just wondering if you think this would be the one or you'd have a better choice.

musicheaven , You can't go wrong with K712 Pro.
It's timber and voice reproduction, frequency extension, accuracy and resolution is as good as you get from an adequately priced headphone.
If you're not a rich person or you don't find spending 1000$ on a pair of headphones   a good idea, grab K712 Pro and you are set forever. 
For classical only , I think DT990Pro would be a second option, they have higher resolution, but a not so good vocal reproduction. AKG K712 deliver both timber accuracy and voice reproduction, for a double cost..

Thanks @AlexRoma good advice and unfortunately for both high tag price headphone and a desire to keep the vocal reproduction quality as high as possible specially for female vocals, it sounds like the AKG 712 Pro is the way to go. As much as I want to get the best mid-price headphone for classical, I can't ignore my other genres. I am just hoping it'll pair well with my desktop setup.

@AlexRoma Thank you, I may of exaggerated their sensitivity to systems but definitely are system sensitive. Oddly I found the K7XX a disappointment compared to the K712, the K712 sounded much better with more fullness, body, and coherency to it. They weren't the same at all despite what people say. I personally liked the K712 more than the HD 650 myself, the HD 600/650 have been disappointments overall to me, they sound a tad gritty to my ears and lacking in transient response, quite transparent though. I have moved on from the K712, I have found the Audioquest Nighthawk(acquired taste) and the DT 480(modded and another acquired taste) to be better honestly, but those headphones are different and hard to compare to others due to their unique sounds. The K712 is one of my favorite headphones, the DT 150 is another great in the mid-tier range.

@kman1211 Thanks for the excellent review and @AlexRoma Thanks for the great extension on kman's words and your own take.  I just ordered the K712s, and I'm super stoked.  Got 'em for a helluva deal, $237.  Not sure if this comments thread is dead, but hopefully someone will respond.
 
I just have a question.  First, I'd just like to get this out of the way...I don't consider myself an audiophile. I'm simply an audio enthusiast who loves high quality sound (and have had PLENTY of experience to understand what good sound is).  Having said that, I like to keep things simple.  I don't really look into amps or dacs or amp/dac combos.  I prefer to be able to get the best sound without having to use a mini generator to power my cans.  Some may frown down upon that, but to each his own.
 
I currently use a ZTE Axon 7 as my music player.  It outputs amazing sound.  The highest impedance headphones I currently have are 250 ohm DT 990 Pros.  The Axon 7 can push the 990s to above acceptable levels.
 
Is anyone here familiar enough with the Axon 7 to know if the K712s will respond well enough to the Axon 7?  My guess is that they will considering the sound quality it provides to the DT 990 Pros.  I do have a Fiio A3 portable amp that works very well, but I prefer not to use it.  I just do not like having the added bulk and clutter.  Again, the keyword is: simple. Audio source + headphones. That's all I ask for. No strings/amps/dacs/cables/cords/bricks/generators/anchors/etc. attached.