Whats a good inexpensive passive pre

If the built-in amps input impedance is high enough for a passive to avoid limiting dynamics, then I would have to second the Axiom reccomendation.

If you just want to get your feet wet...get a Luminous Axiom for $150....even less if you buy used. At that price, you have no risk. I've owned a couple of Lumninous Axioms and they performed quite well.

I bought a Placette and it bested the Luminous Axiom. But, the Luminous Axiom was no slouch by any means.

Here are my two cents worth for the Placette RVC. System matching--finding that synergy of compnents--is most important here.

My RVC has worked not-so-well with some of my set-ups; it has worked, is is currecntly, with other set-ups.

I have never had a desire to sell it. I know that it is an outstanding passive.

Very impressive performance with my EVS Ultimate Attenuators from Ric Schultz of tweakaudio.com, whose bare bones website hardly does justice to his superb products, and modifications.
You eliminate need for a pair of interconnects, because these insert directly into the amp input jacks. So, $350 gets the job done.
Highly recommendable for a single source, perfectionist, simple signal path system, but you still have to get up from your listening chair (?audiophile aerobics) to adjust the volume controls.

If your key workd is inexpensive regardless of inconvenience, then nothing beats EVS Ultimate attenuators. If you don't want to have to reach behind your amp to change the volume, Creek offers good sound for the value, and so does CI audio, both small units with 2 or 3 inputs and priced under $500. I noticed several good advice regarding the Placette, but that may not be considered inexpensive for some. If you are looking at that price range, you should definitively consider the Sonic Euphoria PLC, which can also be remote controled. I has had very favorable reviews, and looks a lot nicer than the Placette.