PREAMPLIFIER UPGRADE QUESTION

@soix, Rhumba 1.3 has 1 fully balanced XLR input and output, while 1.4 has 2 each.

@kjl1065 - I recommend the Linear Tube Audio Microzotl preamp with the upgrade.  It’s below your budget and sounds so good it’s the one component I wouldn’t consider parting with. When I put it in it was the single biggest upgrade I’ve made. 

I think the Rogue is fully balanced, is it not?

As an interim step, if not already, you could upgrade the tubes in the RP-1. I put a set of Mullards in from Andy’s tube services and have really enjoyed them. Enjoy those while you continue research on high grade pre

Also you might try the PS Audio BHK Pre.  That has 12AU7 valved input stage. And you can possibly trial that unit and they give you a decent amount for the Rogue.  Although you proly do better selling RP-1 on your own as people snap those up pretty quickly. 

Audio GD HE-1 XLR 10 tube Pre from Underwood HI FI....It has it's own Regenerative Power Supply that makes it's own power from the outlet...none of the units you list have this technology...Game changer for 2 channel SQ.........$5,000   Read the Part Time Audiophile review.....The best under $12K he's ever reviewed !

These Backertlabs preamps look great. The website however is probably a contender for the #2 spot of the worst audio websites ever designed. Just amazingly bad.