Conrad Johnson vs Audio Research vs BAT vs Cary

Add an Aesthetix Calypso to your ones under consideration. I used to have a CJ Premier 17LS2 and don't miss it, though it was a fine-sounding linestage.

First off, congrats on the Threshold T400, I've owned that, and it is one of the best SS amps I've heard.

Now I've owned many preamps, including the BAT VK-31SE, VK-50SE, VK-51SE, and had extended in home auditions of two others, the VK-32SE and VK-3iXSE. I've also owned the CJ Premier16LS mk II, VAC Renaissance MK II, and ARC Ref 3. Of all these preamps, the ARC Ref 3 was my favorite, followed by the BAT VK-51SE and the VAC. The CJ was too warm for my tastes. I've heard the Cary SLP98 several times, but it was also too warm for me.

All that said, my reco would depend on what you seek. If you're seeking more musical weight and authority, I'd go for one of the BAT preamps. If you're looking for more refined musical detail, I'd steer towards the ARC LS17 or VAC Standard LE preamps. If you're looking for old school tube warmth, CJ or Cary would be the way to go.

Just like ice cream, no one can tell you which flavor you will prefer.

Cheers,
John

If your T400 is DC coupled, you might want to consider how likely the tube pre is going to pass on DC.

Thanks so far for some very interesting answers. Another Agoner emailed me to say he had tried the BAT VK-5i with the Threshold and they were a poor match (probably impedance mismatch). Elsewhere on forums, I think it has been suggested that there is an impedance mismatch. Is anybody aware if the newer iterations of BAT preamps (e.g 31SE, 32SE, 3iX) might circumvent this problem?

If you want to use a tube preamp you will have to run it single ended. The balanced input impedance on the Threshold is only 600 ohms. Any CJ, ARC, or Cary run through the RCA inputs will be fine. The 31SE, 32SE and 3iX can also be used, but not through the balanced inputs.