Is Preamp overkill for me?

The problem of mating a source to an amp can be good or bad, depending on the components.
Many times a direct feed, or just through a passive attenuator, leaves the sound too lean/thin.
A LOT of folks really ned the preamp to alow the music to have the proper tonal balance. All has to do with impedence and loads...
If your stuff works then you are lucky. If it doesn't, then you either have to search for a compatible source/amp combo, or buy a preamp.

Check this out ---

http://www.placetteaudio.com/remote_control.htm

You might consider the Luminous Audio Axiom passive pre. At $150, it's quite inexpensive, you'll get a 30day money back, and the designer will customize it to fully drive your amp.

I second Rsbeck's suggestion of looking at Placette. If you are interested in purchasing new, Placette offers an in-system trial, so you can try it in your system, and if you don't like it, return it.

Or you can get the basic RVC (since you only have a single source) here on A-gon for pretty decent price.

I've got a Placette passive pre that I use with a Wadia 861. Very transparent, very nice.

My 2 cents worth.

Proper impedance matching and making sure there's enough current available for good dynamics seem to be the two things an active preamp is most useful for. I've used a transformer based passive for about a year, and have been very happy with it. I just got a Morrison ELAD, which is a quite inexpensive ($780), well-made active preamp with two inputs and two outputs. It has dual volume controls and a very nice separate power supply, but no other features. My early experience with it in my single-source system is insanely positive.