look at metallurgical's recent reviews of nicehck m6 and bgvp dm6:
http://blog.livedoor.jp/headphone_metal/
to him, m6 is spot on, and dm6 is too thick and dark.
the thickness in these last iems is starting to worry me. audbos p4, tenhz p4 pro, bgvp dm6, toneking t88k.. i understand that some thickness, lush, body, warm, "musicality" (i find this term off to define this sound) can be desirable for some vocals and lows rumble. but please, a hint of it is enough. if over-thickened, it sounds slow, creamy, veiled, dull.
i'd wish to find more 6+ BAs iems in the line of toneking t4 (4 BAs), so clear and resolving. i find their vocals more natural than creamy thick vocals. to me, this is what is nearer to musicality, it's my personal preference.