A lot of folks were asking for a small, high quality, high fidelity stereo Headphone Amplifier: The Synth guys were looking for something to insert into a signal chain to see what the waveform was doing at that point. Folks with amp simulators wanted something for silent practice. Folks with DAWs wanted to check input signals before pressing record. Horn / VoxBox users wanted something to hear their effects levels before the gig (their instruments being too loud to hear an effects mix in the monitors). Music store owners were wanting something to allow people to demo guitars without disturbing other customers. ... And everyone wanted it as small as possible.So I designed and built the Mayfly Headphone Amp. I wanted it simple, no frills, High Fidelity, no coloration, stereo (but able to work in mono), with just a volume control. That's it. No gimmicks or features you don't need - and don't need to pay for. I knew it was a winner when the prototype run was snapped up instantly.Some notable things: It's not an amp simulator - it's a HiFi headphone amp. It's designed to amplify exactly what's put into it - with no colouration. It's Stereo - but with a mono switch for use with mono boards. In mono mode it runs the left channel (tip) to both ears. The headphone jack is on the face - exactly where you want it. No digging around the side to plug it in. It has a through output jack directly wired to the input jack. This is so you can insert it in the middle of your signal chain - very important to VoxBox users and synth players. Kind of like a Y-chord with one leg being able to drive headphones. It's high impedance so it won't load down your signal. Small, simple, perfect. The Mayfly Headphone Amplifier. High quality, high fidelity, stereo headphone amplifier. Stereo volume control. Small form factor: 3.6" x 1.5" x 2" (92mm x 38mm x 50mm). Headphone output jack on the face. Mono switch - runs the left channel (Tip) to both ears. Through output jack (directly wired to the input jack). High input impedance - won't load your signal. 9V DC input. 30 mA.