The Sarno Music Solutions "Steel Guitar Black Box" is a product I've been aware of for a while but never really paid too much attention to. With me recently being asked to look at some full pedal board solutions I started to think about using tube based buffers a'la David Gilmour's Pete Cornish pedal board which uses unity gain tube preamps (buffers ;-) to replicate the input of a tube amp and eliminate the loading effects of long signal chains. The Steel Guitar Black Box does exactly this. Here's the description from the Sarno Music Solutions website:
"The Steel Guitar Black Box™ is the ultimate tone enhancer for amplified musical instruments. It is a simple device using a single vacuum tube, yet it has a profound effect on just about any instrument signal that you pass though it. The SGBB is a true, audiophile quality, vacuum tube pickup driver (buffer/impedance matcher) especially designed for enhancing the tone of magnetic or piezoelectric musical instrument pickups. Originally developed for use with pedal steel guitar, the Black Box is equally effective at breathing life into and enhancing the tone of upright or electric bass, electric or acoustic guitar, mandolin, fiddle, Rhodes or Wurlitzer electric piano, synths and keyboards, drum machines, lap steel guitar, studio mix tracks, and more.
Dirk Hendrik of dirk-hendrik.com traced one of these little beauts out and shared the schematic: http://www.box.com/s/50ae41644b7af8eaa7e8
So if you're looking to build yourself up a front end for a large pedal board here you go - it works like a treat according to all the reviews out there and it's not too complex to build.