Yup I was thinking about upgrading stock cable for quite some time, stock one feels very thin and poor.I am also using the HEKV2 and like it even better after having upgraded from stock cable to a ZMF OFC cable which imho made an already good headphone sound even bettter.
I also experienced some occasional sibilance and overbrightness problems with the thin little stock cable but the OFC much thicker solid copper cable has solved those problems .
It would of course be interesting to compare it to Susvara again using this cable with both.
With stock cables Susvara quite easily beat my HEKV2. But it was not a night and day difference, but a bit warmer, fuller and more refined SQ with Susvara.
And most of my comparisons where made with a Dave/HMS with extra amp involved and my reference hi res masterfiles of symphonic music.
But after listening couple of headphones i feel that he1000v2 is not final word when it comes to refinement resolution and clarity - things that i strive for. Hence I want to try something higher end like lcd5.
Anyway he1000v2 is really pleasing headphone to listen. Especially with classical orchestral type music (but not only) Tonally it's very pleasing and in my humble opinion it could be called baby Susvara (i had opportunity to listen Susvara at the dealer with nice hifiman amp and indeed it was very very good experience)