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


Hello all.
I'm using an Audible Illusions L1 preamp and I think my system sounds better when I remove it from the signal path. Oppo BD105 directly to SMC Audio DNA1 Gold power amp. I have read that there is level of quality you need to hit before there will be an improvement in sound. I can't seem to find what that level is. Any ideas?
Thanks in advance,
Ben
honashagen
I’m pretty sure that’s what I said, isn’t it?
No you were putting ****on the fins, and I wasn’t.
I like the fins, as I said
" they look a lot better than a plain square box."!!!!
http://www.audiocircle.com/image.php?id=151232

Geesh!#! read first, think, pause, then react.
The chassis seems to be used for several pieces of equipment, including amplification, so maybe it is economical ? I like the looks of the heatsinks. @georgehifi I might be ready to try an LDR unit, so what do you think ? Enjoy ! MrD.
Clicking on the links provided, looks like really cool stuff. Well executed, sensible options, and nicely made. 

BTW- extrusions are pretty cheap. Maybe the most cost effective way to build a stiff, non-ferrous box. The designs strikes me as "smart" looking at the pics, like a guy who knows what he is doing and also knows where to source materiels.  
atmosphere, all I could find on the Baxandall was math and schematics. What good is that?