Just joined the mix as a new Signature DJ owner. Will post my impressions when I get them, probably not until early next week.
I had planned on going with the TH900 but after lots of Head Fi reading over the last few days, I was finally able to kick the little devil off of my shoulder that was telling me to ignore my budget. So I am going with a cheaper alternative in the SigDJ.
On Amazon right now the seller "Wiki Deals" has them for $950 and there is a 10% off discount applied at checkout, so I got them for $850. I think the seller only had 1 or 2 left, so get it at that price quick if you are on the fence!
As a background for where I am coming from for when I drop my review next week, the only audiophile cans I have owned are:
Sennheiser HD598 -- Loved the mids and highs but sub bass was almost nonexistent. I listen to a lot of electronic based music so this was an immediate deal breaker
HifiMan HE400 -- Mids were amazing, highs were sparkly and clear and I didn't feel any peaks that bothered me. Bass was detailed and lush...but alas the sub bass just wasn't good enough. I'm sure it was fine from a technical perspective, but there are too many moments in electronic music where that skull crushing feeling is absolutely necessary for the full enjoyment of the music. Had to send them back and decided no more open cans for me
Denon D600 -- Decided to scale back after the HE400 and go with an entry level basshead can. Loved the thick bass in electronic music on these. Unfortunately, finally getting that right came at the expense of everything else. Did not like any genre I played in these other than bass-centric electronic. Muddy, muffled, with uneven vocal peaks caused by frequency spikes.
I can tell from descriptions of the SigDJ that the bass will be worthy enough to justify the purchase. The deal breaker will be everything else. Muddiness/lack of clarity is going to be my main concern. Neutrality is not a concern for me at all as long as the music sounds engaging and immersive.