Please give them a shot after some burn in, as they are from the box
I just let a pair of 671 burn-in at high volume for an hour, and I'm now listening
pros:
-killer comfort: acceptable clamping, very comfy headband, soft earpads, nothing's really touching my ears...it's pretty much up there w/ the cd3k comfort-wise, and that's saying a lot
-headstage ain't bad, especially for the price
-isolation is not inexistent, there's felt on the outer cups. It's not much but it's not inexistent.
cons:
-the earpads don't have pleather at the back, so bass impact is flabby
-the mids are a resonances feast, and it'll take a lot of acoustic foam and so to make it bearable I think. I could foresee that the 670 would sound uber-resonant, reason why I prefered to go w/ the 671...you can always close an open phone, but the opposite is a no-go.
So far, I'm happy....together w/ pleather earpads, ortho drivers and acoustic foam/newplast, it shall deliver what I want: an ortho cd3k basically
EDIT: deep bass is far better w/ the sa5k earpads, lucky me that they fit!