Tube preamp for techno and other bass-heavy music?

From my experience with BAT, Aesthetix and CAT line stages, the CAT really excels at the frequency extremes. Incredible bass extension and authority.

BAT, either tubed or SS will give you good, solid, bass.

A more general answer - When Joule Electra was first introduced, they offered the LA-75 and LA-100 line stage. The difference was the LA-75 had a SS power supply so was less expensive. The main sonic difference was a stronger, more dominant mid-bass with the 75. Those of us who heard the comparison agreed the LA-75 would appeal more to someone listening to rock, reggae, etc.

So one consideration could be to audition pre/line amps with SS front ends, rather than all tube designs.

Also, you suggest you listen to a "decent amount of material in the 20 Hz - 40 Hz range". Unless there is dominant electronic instrumentation, that might not be likely. The open E string on a bass is 42 Hz. How much do you actually hear below that? Most folks are not aware of the real frequencies of the music we listen to. Have you heard a 60 cycle hum from a ground loop or other problem? That's pretty low and many speakers do not produce much below that, yet sound like they produce strong bass.

Anyway, good luck and happy listening.

I listen to a lot of stuff with information below 42Hz! I played string bass in junior high and past college. So I find that bass response is important to me to be convincing, and since I like a lot of electronia, I have speakers that go to 20Hz and electronics to match.

In tinkering with a lot of tube preamps over the last 40 years, I found that the big problem in getting tube preamps to play bass is the output coupling cap. You can make it bigger to get bass, but if you do so you can loose detail as the bigger caps are less musical. So I started tinkering with direct-coupled outputs on the preamp, inspired by an old Berning preamp called the TF-10 (which also had a direct-coupled output). It was a bit of a trick but I got it to work.

Not only do you get deeper bass with a direct-coupled output, you also get more mid and high frequency detail without fatigue- its sort of the best of both worlds.

So- tube preamps thus have the ability to better than the best transistors, IOW deep bass is not an inherent limitation with tubes; it has to do with the coupling caps.

Well, that explains why the VAC Renaissance has superior bass compared to other preamps I've used. It has no coupling capacitors in the signal path. That said, I don't think Rrolack will find an Atmasphere or VAC Ren for under 2K.