vivaslbYou can say the Melos SHA Gold has a copy of the Lightspeed Attenuator MkI con-tactless volume control in it, they called it a photentiometer and it was this that set it apart from all other tube or solid state active preamps, and why it got great reviews, as the tube part was basic tube preamp circuitry. These go for good money S/H if in good working condition.
Melos SHA Gold Tube Preamplifier
Many owners got in contact with me and got their’s converted to a Lightspeed MkII volume control, which sound even better.
https://www.stereophile.com/headphones/796melos/index.html
Cheers George