Having heard both cans, I would dare say they are polar opposites of each other.
Bear in mind I'm used to the more balanced signatures of the Senn HD600's and Shure 840's.
I was also auditioning the AKG K701 at the time.
However, i put on the W5000 and I immediately asked "Where the heck is all the bass?" It felt like there was a hole in the audio spectrum.
About 30 seconds later, I took them off as I simply just hated them. They were far too unbalanced.
The W1000X is much harder to audition, if not downright impossible in the US, since AT only sells them in Japan and I believe the UK.
That said, I did import a pair from Japan, and I fell in love with them.
The bass is particularly present, yet very detailed. I'd say it's a fairly warm can, but it's much more balanced than the W5000. I'm pretty much settled on these to be my "fun" headphones to complement my HD600's sitting in my reference spot.
