How much do I need to spend to get a preamp that sounds better than no preamp?

Sorry broadwayjoe you are not even using simple terms, you simply have it wrong, accept it, if your going to state things, check to see if you have them right.
The volume control from sources such as cdp ,dac, even computers ect do not drive the amp/s, their output buffers do (BIG DIFFERENCE to what you implied), which as I pointed out are more than up to the task, in most cases.

Cheers George

To George and all. I have been listening to my Luminous Audio Axiom II with Walker mod, single ended 3 in 2 out, with remote, for a week now, and I have to say, I am connecting with the musicians, as well as the mixing and mastering engineers who have worked on the recordings, like never before. A veil has been lifted, the colorations are gone, and nothing is missing from using my 2 expensive preamps ( will not mention what they are ). I am feeling lucky ( punk ), that the synergy is working for me, and quite happy I made the move. The background is dead quiet, as there is absolutely no noise, hiss, hum ( etc. ) in my system. Thank you George for steering me in this direction, as I always thought an active preamp ( with gain ) was absolutely necessary( and I have been at this for 50 or so years ). Of course, experimenting with my pro amplifiers, with their built in volume attenuators, allowed me to hear this as well, but now I can use my favorite little amplifier, which I could not, successfully, use before. Cheers ! Enjoy ! MrD.

I am feeling lucky ( punk ) ....

Lest anyone wonder, this is a humorous reference to a famous line spoken by Clint Eastwood in the 1970s film "Dirty Harry."

Congratulations, MrDecibel.  As you said, enjoy!

Regards,
-- Al 

Al, thank you, and I am glad someone caught the line. Enjoy ! MrD.

I just sent my Axiom back