What is the quietest preamp you've used?

Can you also please tell me whether you were using balanced or se ins/outs? Thanks.
Audio Zone PRE-T1 transformer-coupled passive preamp with RCA ins/outs.
Audio Research LS25 "Balanced" So quiet it was scary.
Plus it was the BEST pre I ever had.
My Rowland Coherence II. It is battery-powered and dead quiet. It is a fully differential balanced design.

You pose a very important question. It was not until I lived with a super-quiet preamp that I understood the importance of noise to a preamp's performance -- low noise is crucial to high performance in a preamp.
Creek OBH-12
Creek guarantees it to not affect the music one bit.
Totally passive unit.
Pass Labs X1 using balanced ins and outs.
Manley Shrimp w/RCA's. Unbelievably quiet...that's why I bought it.
The most quiet was my old (now almost 23 years) Perrauex SM2 bought in 1983. It was a slim design and was a highly regarded pre amp. Although extremely quiet with almost no noise or hiss... with comparison by todays pre amps its most likely anything but neutral.
The Von Gaylord LAD-L2
My Krell Krc 3 was dead quiet.
Rogue Magnum 99 pre amp with RCA outputs, and my Manley Stingray (integrated amp)was so quiet at full volume you had to have your ear 4" from the speaker to hear any hum. So a vote for Manley stuff being quiet...
Boulder L5ae preamplifier, balanced in/out to Boulder 102ae amplifier.
First Sound MK11, had a AUDIO RESEARCH LS25 this one is much quieter
Spectral DMC10-delta - Every circuit, including the phono stage was totally silent.
Agree also with Philjolet...Its amazing how quiet the tube Stingray is.
Rega Hal. It's dead quiet.
I have a Counterpoint SA-3 that is so quiet no sound even comes out of it.
Dehavilland Ultra Verve, First Sound Presence Deluxe mkII
Audio Research LS 10 solid state preamp using balanced interconnects...it was run through a BPT line conditioner.

Dead quiet...eerily quiet. The sounds came out nowhere in a pitch black background.
In terms of tubed preamps the quietest I've yet used, and to a large degree, is my current Herron VTSP1A/166. It is fantasticly quiet as well as great sounding. If you are up to considering tubes, I highly recommend it. It's completely single ended, as is the rest of my system.
Krell KCT
Bent Audio NOH :)
Another vote for First Sound Presence Deluxe mkII. Absolute silence. Shhhh you can hear yourself breathing. ;-)
20 posts and 20 different preamps, this is great. Gotta love the gon
I've spent a lot of time with Krell pres and owned Pam 1 & 3, KRC-3 and KCT. However; my latest pre is a two box Classe CP-65 and I have to admit, it is dead quiet, more so than the Krells, although; they were quiet also.
Pass Labs X0.2 using the balanced inputs and outputs.
The quietest amp I,ve ever heard was an old APT Holman that a friend of mine had dumped years ago and want it to sell it to me. When we tried out it didn,t worked at all, so yeah I guess thats the quietest preamp I,ve ever heard in my life.
Krell KRC-3, balanced outs.
Can you clarify what you mean by '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
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.
Among tubed preamps, I doubt that there is anything much quieter than the First Sound. The ear-to-the-speaker test yields absolutely dead quiet at normal listening levels. There may be solid state units which test quieter, but I doubt that the difference could be sonically significant. Great dynamics and low-level detail out of the First Sound due to its quietness.
The quietest is ALWAYS going to be a passive device. You just can't beat that for transparency. However it has other shortcomings that are generally bettered by active stages.

von gaylord active pre-amp on their integrated
Ayre K1-xe, Excellent solid state pre!
cat ultimate