I suppose I should try my Telefunken ECC88’s I got from Upscale audio before my BHK arrived. But before that happened, I noticed one of those tubes had the exact same date stamp with gold letters that the guy at Jacmusic.com had that bought similar ECC88’s earlier than Kevin. His batch was bad. I suspect that most likely what happened was there was a big batch of used TFK ECC88’s in Eastern Europe, so these guys relabeled them and stuffed them into new boxes. Jacmusic’s tubes were worn out, so the sellers just tested theirs and picked out the good ones, so Kevin (I suspect) has those for sale. (There was a way the TFK embossed logo on the base of the tube could be faked, also, per the Jacmusic site)
So I never put in the ECC88’s.
But I did put in a pair of PCC88’s into my BHK, and WOW, the detail improved a LOT. I got more dynamics and more detail (MartinLogan Spire electrostatic speakers)
And the PCC88’s are cheaper, to boot!