I'm looking for a schematic for an Eden WT-400 or similar. I have an AMP SL-1 preamp that has an on/off button for "Enhance". Since Russ Allee was involved with both the SL-1 and Eden designs, I figure that I can use his later work to figure out a way to make my Enhance function variable instead of all or nothing. I have a schematic for the AMP BH-420 (thanks Brian and Brad!!!) but understand that the SL-1 is slightly different. If someone has a schematic for the SL-1 and would be willing to share, I'd really appreciate it!!! Thanks (in advance) for your help!