I'm not speaking from any experience whatsoever for aftermarket cables for TH900, and I will stand corrected if I'm wrong, but low efficient headphones like TH900 "which has a great cable to start with" don't really benefit from re-cabling at all, the only efficient headphone I know that does is some Grado phones.
Early on in this thread we concluded that there were no benefits for re-cabling this phone, some peeps that did re-cable balance or SE said they sounded the same as stock.
My own experience and personal belief is aftermarket cabling can improve SQ greatly depending on the application, I use aftermarket cabling in my current rig so I'm not a hater of it. If there were a noticeable +difference, I would of done it already.
If anyone has 2 TH900 one stock cable, one aftermarket cable, and can put this to rest once and for all it would be much appreciated.