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The universal charger's LED shows red when charging and green for complete. There's also a downfiring LED in the middle of the Acrylic front footer of each bamboo brick. Its glow reflects forward just enough to show green below the component for operational battery status, red as a warning that playtime is just about to expire. [My sample was encased in an earlier enclosure. The edging around the display has since improved a lot I was told.]
Channels are switched manually with a 3-pole toggle. It runs through the sequence left to right or right to left. The always-on green display confirms the active input with brackets around the corresponding number while the numerical volume display shows actual dB of attenuation. -62dB is mute, 00dB full power. The switched resistors click audibly from relay to relay as volume is changed.
The attractive 8-button remote with embossed Libretto name is optional for the amp and only offers volume up/down.
Rear panel accommodations are basic. The mains charger seats in the top socket of the amp, the charger umbilical to the power supply in the one below. Then there is a beefier multi-pin lock-collar power umbilical that's long enough to stack the units or place them side by side as shown next. The orientation of the Euro-proof speaker terminals has their spade slots angled inward which gets a little crammed. I'd have the two left terminals angled outward to create more space. The right ones have to remain as is to clear the power/charger leads. The shipping carton is a special fabrication with wooden side handles and velcro flip lid, foam liners and cradles. It completes the organic theme of the Human Audio delivery.
Though this amp is not expressively designed for this purpose, I had on hand a 50-ohm orthodynamic headphone of low 83.dB sensitivity that required high-output break-in. I thus stapped this HifiMan HE-6 to the Fortepiano's speaker outputs with a 4-spades-to-4pin-XLR leash. The Hungarian amp + power supply successfully tolerated this high impedance without any distortion, noise or signs of distress. Instead things sounded very good. I thus mention it as a possible application. Low-impedance headphones can be run balanced—i.e. with discrete left/right channel grounds—for which they only require a custom wire harness that terminates in spades or bananas. Headphones like AKG's 701/702, the three Hifi Man orthodynamic models and the Audez'e LCD-2 equivalent all sport disconnect wiring either via mini XLR or screw terminals. Rigging up a balanced replacement harness isn't difficult.
Of course speaker drive/listening is the main purpose of this amp so that's what we'll get to now.
