Promitheus Audio Reference 1 TVC - Price: $375 shipped
Typically volume controls throw away excess energy as the volume is decreased while a Transformer Volume Control (TVC) instead uses a transformer to convert the drop in voltage to increased current. As such this preamp uniquely sounds sounds better as the volume decreases. This makes a TVC the perfect preamp for those who like to listen at more reasonable levels, or for those with high gain amps. As for a sonic signature, this doesn't have one, its a perfect pre amp with no alterations to the sound whatsoever.
This passive pre was made by a company called Promitheus Audio out of Malaysia. This particular unit is an upgraded Reference version of their TVC which includes improved transformers, pure silver RCAs, pure silver wiring, and a stainless steel base. The Ref 1 features 1 input and 1 output for the cleanest signal path.
My particular unit has additional improvements, including a ebony knob, copper top plate, vibropod feet and blackhole pad damping material on the transformers and base plate.
I am the original owner and this has been used very lightly in a PC rig for ~6yrs. There is a light scuff on the volume knob and the top plate has some wear. See pics on Flickr for details.