Not much info on this but, it’s a rare West German Schaller vintage “Treble-Bass Boost” from
1968. It typically goes for over $400usd, so fairly desirable. It’s a 2 transistor based booster, with a five
position switch that controls the the frequencies being boosted. There’s 2 treble settings, 2 bass settings, and 1 mids setting. Seems like it also gives a little bit of drive too, which is a nice addition.
