@Sakahara
I wouldn't judge KR bad so fast, unless you have had that experience already...
May I ask you which Sophia's did you buy? Thing is, at least with TJ's, where Sophia's are coming from, that the less expensive pairs aren't that good with keeping the bias and that's very well known problem with them, however Sophia's suppose to have much better quality control. I owned ceramic based Mesh plated, but the most expensive from their line with 1 year warranty and never had any issue with bias or unbalanced L&R.
I sold them and probably will never buy again, KR and AVVT's are my reference now. My next pair, probably, will be KR Balloon 300B, which seems to be better than reissue WE's and they are USD 525 a pair with 2 years of warranty http://www.kraudioproducts.com/Kr/ProductDetail.aspx?CatID=13&ProductID=3
Dont get me wrong guys, but most Chinese tubes are trash and the very small production line, which are also very expensive, are one to get, but than again, even Sophia's so called Mesh aren't really Mesh at all. I say, buy tubes from manufactures who developing and producing good quality tubes, support them instead of some who don't develop a single thing and just re-brand and re-sell.
Thanks for sharing and good luck.