Passive Preamp Recommendations?

The Goldpoint SMD resistor passive and Endler Audio Stepped Attenuators I have here display a purity of sound that is very nice at first, but as time goes on you realize there is a level of dynamics and tonal density missing, compared to active preamps. Resistor based passives are also quite sensitive to impedance matching and can sound terrible in the wrong set-up.

Transformer and autoformer passives are said to resist this trend, and can even provide 6dB of gain. The Music First Audio preamps fall into this category.

I have to agree with those who like buffered passive preamps since the buffering helps prevent losses from long interconnects and impedance mismatches, and seems to restore dynamics and tonal color. My McCormack TLC-1 has been completely tricked out by SMc audio and is essentially a buffered passive that achieves 6dB of gain through Lundahl output transformers. This is the best preamp I have heard out of many, including several approaching or exceeding $10K.

Take a look at Tortuga Audio and the passive they have come up with. All the reviews rave about it. I bought a board recently to start a DYI project to try it out.

I use what is in effect, a clone of the MFA Baby Reference, built by a Hungarian gentleman. It uses the same transformers as the Baby Reference. It feeds into the ARC reference 75 Power amp and is very impressive. I got the idea from a HiFi+ review of the ARC 75 with an ARC LS27. The reviewer had a baby reference to hand and felt the Pre's were different not better than each other, the passive more air and refinement and the LS27 more slam.

I briefly heard my new 75 with the dealers Reference 3 pre, when it was delivered. Too short a period for proper comparison, but I agree with the HiFi+ reviewer and prefer my Pre. It cost by the way, £950, which is less than the current price of the S&B transfomers, so all in all a good deal.

I have a re-capped Conrad Johnson Premier 140 amp. I use the KT120 tubes and have a nice Amperex in the 6922 position. I have been driving it with an Airtight ACT3 ($7550) I have tried all sorts of tube from Brent Jesse. In finally landed on a great Amperex in the 12AX7 position and Mazda in the 12AU7 slot. I though I was done. Very clean, balanced, totally non fatiguing. I was very happy. Then a friend mailed me a Khozmo passive preamp. The thing new cost about $500. Outside of the volume pot clunking around when you turn it, I just cant match the presentation with my Airtight. Turn on Behind Blue Eyes by the Who, and the vocals + guitar make you want to cry. It is so fine, airy and full of tone. This may be in part that I know really realize what a wonderful amp my CJ is. Bass, it is all there for me. Much more clear and tight. Even when I put the Teefunken and RCA back in I could not get the clarity. Also, when I first plugged the Khozmo in, I though it did not work. There was absolutely no hiss coming from my tweeters. Black. That is until I turned the volume and music came forth. If you have a nice tube amp, you don't need an active pre. It just adds more tubes and headache. I have not attempted to sell my Airtight yet. I am going to try some other passive. I just don't like my volume clunking all over. Plus I am thinking remote might be nice, so Tortuga? Anyhow, don't discard the idea of passive. If you have a nice tube amp, give it a try.