It's very well build and sounds great, own one. Connectors are not loose, same fit as stock, the cleanest soldering I've seen (disassembled the plug), not sure I understand comment about length, it's 2.5 m, if you need longer get one, they have 6m I believe.
Do a search on Zy cables here, it's elite cable builder well known all over China. You may have exposure to one of the earlier revisions perhaps, I've read that first version of HD650 had some lousy connectors, but that was fixed long time ago, not sure about HD800. In fact, I liked it so much that I ordered one for HD650 as well.
And yes, unless there is bad soldering, some shorts or some other kind of the mechanical problem, any cable will sound the same. Add fancy braiding, some poetry filled manufacturer description, a couple of peer reviews, and all over sudden same cable material and geometry magically fixing bright treble on one phones and adding bass on another.
HD800 cable, same as T1, is balanced by nature, little DIY and you get balanced cable with SE dongle.
BTG Audio and Moon Audio are two others budget minded alternatives to Zy cable and DIY retermination. I dare anyone to tell the difference in unsighted ABX.