What is the quietest preamp you've used?

Nagra PL-L. Easily the quietest and most transparent. Ayre K-1x was also quiet (but a bit drier than the tubed Nagra)

Krell KCT but qualified as "dead quiet" in combination with a 400cx amp connected via CAST.

Since were talking ONLY about noise and not any other factor, I would guess either Krell or Boulder. Interesting to see all the answers.

Solid State - KLYNE AUDIO ARTS 7LX3.5/B using balanced
Tube - FIRST SOUND

Herrons. Take your pick of model, tubed or ss.

I've had mainly tubed preamps for the past few years including the First Sound, the Rogue, a Joule-Electra LA100 MkIII, CAT.

I wouldn't call the Rogue 99 Magnum "quiet", although it's nice sounding and certainly quieter than the two versions of the 66 I had.

My First Sound Presence Deluxe MkII was indeed quiet.

My current preamp, the single ended, tubed Herron VTSP-1, is the quietest preamp I've ever heard, other than the cutom built ss CTC-Blowtorch. I love my Herron.