Meze Audio 109 Pro Speaker Amps Sophia Electric™ 274B tube is

Sophia Electric™ 274B tube is a premium rectifier tube for 5U4/5R4/5AR4* direct replacement with 3X longer plate structure

improved bass definition

Rubidium 10MHz master clock module at the core

Value-minded audiophiles who want a planar magnetic open-back headphone with wood aesthetics and genuine high-fidelity performance at an entry-level price point

15W RMS / 300 ohms

Meze Audio 109 Pro Speaker Amps Sophia Electric™ 274B tube isMeze's flagship dynamic driver headphone, the 109 Pro represents the company's most refined statement in open back dynamic design, built around a custom 50mm dynamic driver and the premium craftsmanship that defines everything Meze makes. Type and Technology Over ear, open back, dynamic. Custom 50mm driver with a polyurethane diaphragm developed specifically for this headphone. Zinc alloy yoke, self adjusting headband, and premium leather earpads.