Looking for warm tube preamp (should pair well with Pass power amp), budget $6000

I use a McIntosh C2300 tube preamplifier bought new in 2008. I replaced the Chinese made "McIntosh" tubes inside it with NOS Telefunken tubes. I use it with a McIntosh MC2205 power amplifier. Very, very pleasant sound. 

LOL!  Nothing little about the SLP 05.

Same for the SLP-98. It's only little if you don't count the "loaf of bread" power supply. 

I think any Mac tube (or solid-state for that matter) runs on the warm side of neutral. 

I'm running an Aric Audio Super 6SN7 right now on my Pass Labs XA30.8. Its a wonderful match. I would look into the Aric's Motherload II as its in your price range and might be worth your consideration.

Good luck