Based on what you are looking for, the Joule is the obvious choice. The impedance issues here are no issue - your amp can be driven by any preamp.
Joule Electra 100 mkiii vs. Musical Fidelity A3cr
I have narrowed my preamp search down to one of these: Joule Electra 100 mkiii OR Musical Fidelity A3cr. One of these will be in front of a Cary V12i tube amp, and Maggie 1.6 speakers. I'm interested mostly in getting the widest/deepest soundstage with tube warmth. Your experienced opinions are much appreciated.