paulf707
Thanks bitflipper... which Senn's do you use?

HD-558

Thanks....
Still struggling to decide between Sennheiser and AKG

very little difference other than around the high/mid... not sure that I'd be able to tell the difference anyway!
I'm considering using TB-Morphit as well (and all of these options are available in Morphit)
 
I'll update this post when I come to a decision...

From what I can tell most people consider Senn more comfortable than AKG, even though they weight a little more. I'm still considering the ATH R70X as well. Super light.

I just discovered something that may relate to the whole speaker/headphone "breaking in" thing. I work for a company that makes billions of tiny $0.50 microphones for cellphones and laptops. We measuring up to 150dB SPL by building a fixture around a 100W horn compression driver and placing the mic within a few mm of the grill down in the throat of the driver. It gets pretty loud in there. What we've just discovered is the speaker fatigues over time resulting in fairly substantial THD degradation. It starts with enhanced 2nd order distortion, then 3rd, then 4th, etc. So I'm thinking people like the warmer sound of broken in speakers due to their increased distortion caused by fatigue.

So it's not so much 'breaking in' as 'wearing out' 😃

Save yourself money and get the Logitech G35 7.1. Been using them for years. Great because they don't color the sound; total flat response (which is what you want)

I use headphones for all my mixing these days. You have to know what you're doing, but in my opinion its not really necessary to mix with speakers in a treated room...if you use the right headphones and know what you are doing.
 
You mention DT990s and up until last year, when I upgraded to AKG 712's...one step down from their top of the line cans ;), I actually used the DT990s. Whilst not as open and clear as the AKG 712s, along with being not as bass responsive...I could not recommend a better set of headphones. Better built than the AKGs too. 
 
The key to mixing in cans is knowing what to listen for i.e. transients etc, and proper gain staging. Meters like the one now included with The Adaptive Limiter will hold you in good stead, as will the RMS and 'fake' lol VU meters scattered throughout Sonar.
 
Here is an example of what you can achieve with headphone mixing only https://www.youtube.com/watch?v=KCycBiafWAo&t=6s although I've gone back and re-touched this mix...mainly because when I mixed and mastered it for this audio-visual work, I was pretty fatigued and had cut a little too much in the low-mids, as well as, I didn't re-tune the transients properly between the tape sim stage and the compressor stage. 
 
Oh, and no matter what...your headphones should always be open for mixing in the cans.
 
Ben

Mixing on headphones is different from speakers in a room because of the removal of room ambience and bass reflection which is why it's difficult to gauge over headphones. Even $1,500 headphones won't be flat however they will be tuned to have a better performance over the expected hearing range.
 
In the absence of speakers at night for mixing I use sonarworks reference 3 to calibrate my AKG K702.

i would never mix on headphones.
spot check, yes.
check for translation, yes.
micro edit, yes.
enjoy listening, yes.
mixing, no.

Thought you might be interested in this post from a little while back:-
 
http://forum.cakewalk.com/Track-Completed-Mixing-Mastering-with-Headphones-HiFi-m3594580.aspx
 
I've just purchased the Waves NX Virtual Room to help with my mixing and mastering (haven't had a chance to check it out yet - managed to get it on offer from waves $39 down from $99, there are also coupons out there).  The point being that through headphones alone, you don't get the crosstalk (interaction between sound waves from the 2 speakers) that you would get in a studio with monitors/treated room.  I've found recently that I need to check my mix through a couple of options, even before mastering.  In fact, listening to the mix through a £29
 
As an aside, I've found recently that I need to check my mix through a couple of options, even before mastering.  In fact, listening to the mix through a £29 bluetooth speaker was especially useful.