Massdrop x Alex Cavalli Tube Hybrid Headphone Amplifier ———— Contents: Amplifier, Power Supply, electron tube, Cloth Storage Bag, box. New Opened Box Condition. ————- Built from the ground up by Alex Cavalli, a legend in the world of headphone amps, this hybrid amp combines a solid state section, a tube amp section, and an entirely new circuit design. It delivers the current required by planar magnetics, along with the voltage drive that dynamic headphones need to perform their best. It’s quiet enough for sensitive headphones like the Massdro