TC Electronic Integrated Preamp

Here's a loud one for you (I am not responsible for any blown speakers that may happen as a result of you building this thing! haha)! It's a popular preamp and used as a booster by the metal band Meshuggah. It apparently sounds best run at 18v. I didn't include an onboard charge pump since I know a lot of you prefer different methods for that. Should be plenty of room in a 1590B for a daughter board with your preferred charge pump. Schematic can be found here.

TC Electronics Spark Mini

Here's a work-a-like for the Spark Mini. It'll be a bit of a squeeze, but it should fit in a 1590A. The original is all SMD components, so the transistors listed below aren't the same as the original, but through-hole equivalents. Other NPN and PNP transistors can be used (2N5088/87, 2N3904/06, etc.). Here's the schematic for reference (requires FSB login).