Tube Preamp Recommendations?

In your price range I would certainly look used to get more bang for your buck. This looks like a nice choice in your price range here:

https://www.audiogon.com/listings/tube-joule-electra-la-100-mk-11-excellent-condition-2017-04-02-pre...

No relation to the seller Joule is a well thought of well reviewed brand thats still serviced by Signature Sound in NY. That's a classic audiophile preamp.

This unit also looks nice:

https://www.audiogon.com/listings/tube-granite-audio-770r-full-function-tube-preamp-2017-03-31-pream...

Not as well known but Granite Audio is still around and has a great rep.

Just a few thoughts and buying used at the right price is a great way to "audition" preamps in your system, it's easy to flip a good piece if you bought it right in the first place. Good luck.

Thanks for the responses, everybody.  I've spent a ridiculous amount of time researching pre-amps and it had gotten a bit overwhelming for this newbie.  I appreciate all the thoughtful comments.  

Kalali, the impedance of the ProAcs is 8 ohms. The NEW A-20 amp is rated at 20 watts at 8 ohms.  I must confess my ignorance about whether the amp has low input voltage sensitivity and/or the speakers are efficient/sensitive.  Do I need a preamp with some type of gain reduction given that i listen almost exclusively to the Aires Mini?  At some point I'll upgrade that to a higher end streamer plus stand along DAC.  

My budget is about $1,600.  The Allnic L4000 looks great but clearly out of my price range.

Mechans, I am definitely looking for some 3D magic.  I tried an SP9 (I realize it only has one tube in the line stage) since it was easy to borrow, but the sound was too bright and sterile for my taste.  I'd hoped an SP6 or SP8 would be warmer.  Sounds like that's an incorrect assumption?

Are the AI Modulus 3A and ModWright LS 100 on the cooler or neutral side too?  It looks like tube rolling on the AI isn't really possible (lots of people report burning out tubes quickly when they use tubes not recommended by the manufacturer), but is possible with the LS 100.

Gdnrbob, the Atmasphere looks interesting, but the exposed tubes won't work in my home.  Is there another 6SN7 preamp that might fit the bill?  6922/6dj8 seems to be very popular.  Are the 6SN7s warmer?

Thanks again!

Not sure what causes you to think the Modwright LS100 is a bright preamp; far from at least in my listening experience. Drop in some NOS Sylvania , or even Sophia Electric 6SN7s and enjoy

Think about Allnic.  Great sound and great backup service.  I have had the L4000 for six years.  I bought it second hand on the gon.  The batteries leaked in the remote and destroyed it.  Kung Su Park sent me a new one free of charge even though the amp was way out of warranty.

If your budget will stretch you can get far worse than the Allnic L4000

How about an Atma-Sphere UV-1, used.?