You can forget all these above mentioned choices in MHO! For the money, performance, build, etc, you absolutely can't beat the Pass Labs Aleph L and Aleph P passive/active preamps!!! If you only need RCA in's/out's, then the Aleph L is all you need (and one sells on Audiogon right now, just listed, for $850!!!...was $2k). If you need balanced in's/out's, then the Aleph P is what your after! (one selling from a store with remote for $2300 on Audiogon currently!)
I've tried quite a lot of different passive unit's over the years, and these make the most sense!..and sound world class!(virtually not there!...and resolution a plenty). They're also build like a tank!! These Pass preamps are completely passive, until you get some way up the volume control, then active circuit kicks in!...still sounding terrific! I've, again, tried quite a few world class preamps, and these are the only solid state passives I'd consider if It were my money! Have fun...