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

@mrdecibel , IME, impedance matching (not matching as in "equal" but rather low to high as you move down the chain) is more important than gain. If it were not, you could simply increase the output of your source...to 4V or 6V, but that alone doesn’t seem to cut it for many listeners. Most sources (even those with sufficient voltage gain) cannot suitably handle the impedance changes that occur as the signal passes through the volume control and through the interconnects. Aball does a nice job of discussing the benefits of buffers a couple of post ago. There are trade-offs, and personal preferences, as always. Having less circuitry can sound better to some, but only if the ancillary consequences are not deal-breakers.

BTW, Steve McCormack (SMc Audio) makes one of the best sounding buffered preamps you can buy - the VRE-1C. That unit is the culmination of a career’s worth of research and trials going all the way back to his early Mod Squad/McCormack days with the Mod Squad Line Drive, TLC- 1 (Transparent Line Control), and Micro Line Drive units. You can order the VRE-1 as either a unity gain unit, or with 6dB gain through the high-end Lundahl transformers he uses. Most order the +6dB version as Steve believes the differences between the 0 and +6dB gain versions are virtually undetectable. I have tried both in my (very similar to VRE-1) unit and own a 0dB gain version. With 1.5M balanced cables to my monoblock amplifiers, I cannot hear any loss of signal, bass, dynamics, staging, or anything, compared to the +6dB version.

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. The upgraded/revised versions which have balanced inputs, all have a 10K ohm input impedance, which would generally be difficult for an unbuffered passive volume control to drive without some sort of signal abberation. My own trials with passive and autoformer preamps have mostly been into my Clayton amplifiers that have 100K input impedance, and the result has always been similar....an attractive purity but also a flatter, less dynamic, less full-sounding, somewhat bass-shy, and overall less satisfactory sound compared to what I hear through my active buffered (unity gain) preamp. BTW, I heard Steve does an outstanding job modifying/upgrading the Micro Line Drive unit so you could consider that. He also works magic on the TLC-1!

@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.