this was tamed by moving from NOS Amperex (D-getter 6922, BB and Orange Globe 6DJ8s) to '60s vintage Mullard, Blackburn factory ECC88s.
Thom_s
I would agree. I wish I had discovered Mullard Blackburn tubes when I owned my FS Presence Deluxe II. While I owned the FS, I used several tubes (PQ, SQ, CCa, White Label, Orange label...if they made it, I tried it) from Siemens, Amperex and Phillips. None had the magic and sweetness of the Mullard Blackburn tubes as I subsequently discovered while using another preamp.
If you can't get the sweetness the First Sound preamp with Mullard Blackburn tubes, then it's time to move on to another preamp.