The Julius Futterman H3 OTL amplifier from the 1980s is a beast of analog engineering—it runs massive parallel banks of vacuum tubes to pump high current straight into speakers, completely bypassing output transformers. This OTL (Output Transformerless) design eliminates transformer-induced phase distortion and frequency rolloff, giving you brutally direct signal path from tube to driver. The tradeoff? Insane tube count, heat generation, and the need to match speaker impedance carefully since there's no transformer to buffer it. Pure voltage-to-current conversion with zero magnetic coupling in the chain. This is what happens when you solve the impedance matching problem by throwing more glass at it instead of iron.