BrownBox

AmpRx is a Nashville operation co-founded by violinist Cassandra Sotos and bassist Clark Singleton. As working musicians, they built the BrownBox to solve a universal tube-amp problem: modern wall voltage runs hotter than what vintage circuits were designed for, robbing amps of their sweet spot.

The BrownBox plugs between your wall outlet and amp, using a proprietary 5-amp transformer to reduce and stabilize AC voltage. A backlit LCD displays real-time voltage and amperage so you always know exactly what is hitting your tubes. Two grounded outlets handle up to 540 watts, enough for dual-amp rigs or big Marshalls.

Think of it as a safer, smarter Variac. Eddie Van Halen famously used a Variac to starve his Marshalls and get that compressed, saggy brown sound. The BrownBox does the same trick with fuse protection and filament soft-start, so you will not fry anything. Spotted on stages with Red Hot Chili Peppers, Iron Maiden, Derek Trucks, and Bonnie Raitt.