First Sound Preamp Owner's - What NOS tubes?????

Philips SQ E188CC. These add a little warmth to the FS which it needs. I prefer even a little more bloom than the FS can give.

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.

Anyone have a good source for Mullard tubes? Looking for a pair of Mullard E188CC tubes.

Mullard E188CC tubes are often labelled as Phillips. I believe some were made in Holland, and others made at the Mitchum, UK plant. These tubes on E-Bay are Phillips, made by Mullard in the Mitchum, UK plant as indicated by the "R" in the date code.

A Phillips (or Mullard) tube made in Holland would have the Delta insignia preceeding the second line of the date code.

I have never seen a Mullard labelled E188CC, nor have I ever seen any advertised for sale. Well, not true. A seller had a large stock of Mullard E188CC tubes, but he admitted they were relabelled E88CC tubes. Why they were relabelled was never determined, but basically they were not E188CC tubes.

Mullard E88CC Blackburn or Mitchum production are fairly easy to find.

The MIT PPFX capacitors are contributing to the lack of sweetness and bloom. I would change those caps, otherwise IMO sell the pre-amp.