Mjolnir KGSS HV electrostatic headphone amplifier, in excellent condition, with Pro Bias output. I bought this amp in late February (2022) as a "one-off" special from Mjolnir, shipped from Iceland. It is the latest revision of Birgir's prior KGSS HV design, completely refurbished and fitted with his newest constant current source [CCS] power supply. I have used (and/or am still using) this amp with the Stax SR-L500 Mk.2, SR-L300LTD, SR-L700 Mk.2 and the SR-007 Mk.1, all with pleasing results.

NOTE: This amp is sensitive to the mains power feed; therefore it was offered as a "one-off" special on the Mjolnir website (and was offered below the typical retail price for a KGSS HV, which is now $2750). Specifically, the neutral and ground should be at the same (or very near the same) potential or humming can ensue. Birgir/Spritzer (the amp's builder) recommends a very good power conditioner (like a PS Audio Power Plant) or a good full isolation transformer to ensure proper grounding conditions and optimal amplifier operation.

Asking $1795 USD [obo]. Buyer covers ConUS shipping.