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

@mitch2 I have owned a few pieces of Steve’s equipment, including his original line drive unit ( which I understand was not buffered ). I still always preferred a preamp. Maybe I should try a device as you are suggesting. BTW, I always read your commentary ( which is again why I questioned the receiver / integrated amp thing a while ago on that thread ). I do not claim to be the smartest guy with this technical jargon as many of you seem to be, but I do have an understanding of much of it. I am, and have been, an audio guru to many, with my many years in this hobby, including professionally, and the ability and experience to use and trust my ears ( and thankfully, they are still working in my mid 60s ), and that is what I go by. Thank you, Enjoy ! MrD.

Regarding Steve’s McCormack amplifiers, I believe all of them originally had a 100K ohm input impedance, up to the DNA-500, which was designed with a 10K ohm input impedance.

Yes these lower (10kohm) later amps will not be a good match for passives.
But! as the OP used it, direct from a 100ohm source to amps, no problems so long as the input sens is still 0.8v or even 2v for full output, it will to many still sound better than any active preamp, with or without gain.

Cheers George

I think it is worth mentioning that the OP's Audible Illusions L-1 preamp has a gain control and a master volume control. So one can set the perfect amount of gain for the amp and then use the master volume control there after.

Yes Audible Illusions are a very good active preamps, I owned an AI 3A and loved it.
They did run the tubes very hard in it though, you don’t get much life out of them, I’ve always believed that’s why it sounds as good as the best active preamps I’ve heard.

But the OP and me, going direct sounds the best for transparency and dynamics, and to me and many others a well implemented passive comes in a very close second.
To me any active stages add colouration's and cannot improve on the dynamics against a well implemented passive, they can only detract as they have no dynamic range expander circuit in them, and they wouldn't want to as they sound rubbish. 

Cheers George