Promitheus TVC preamp
The Promitheus is a transformer volume control, aka, TVC. Initially when first using such a unit to change volume up and down, one is struck by the sameness of character as the volume changes. With all resister type controls, which is probably 99+% out there, raising the volume also seems to increase a sense of fullness and frequency extension.
During the past couple of years, I've listen with some nice tube preamps with a Mapletree, an Audible Illusions, a Van Alstine and a couple of passive preamps. Positively speaking, the passives always seemed to let though the subtle details, allowed for a sense of speed, and let through the deepest bass notes; the actives made for warmth, smoothness, body, dynamic contrast. Negatively speaking, the passives seemed thin and dry; the actives seemed to veil some detailed nuances buried in thickly textured music, had their own distinct character, sometimes closed-in the sound stage and called for constant tube rolling. The Promitheus, oddly seems right between these two types of preamps, having mostly the virtues of each.
The greatest virtue of the Promitheus, for me, is the body added to midrange and midbass voice and instrument. By "body", I think others called "image density", "fleshed out", "rounded" "wet". This is like a tube preamp, but retaining the see-throughedness of a passive. When a voice or solo instrument is playing, there is a sense of being able to reach out and touch it. And the body has strength, meaning increased dynamic punch.
Another virtue is a new sense of quietness. Sometimes a tube preamp seems to filter some high frequency electronic atmosphere, even though it might hiss or hum a bit. Neither the few good solid state preamps nor the passives I've heard do this quieting. This TVC does this. There is not the slightest hiss though, but hum can be induced if other components are not carefully situated, as I found out when a power amp was placed directly beneath the Promitheus.
Speaking of amps. These characteristics were true when going into a Decware SE84CS, a gainclone, and a battery powered T-amp.
Weaknesses in comparison to either the passives or active tube preamps: a bit of horizontal spacial restriction, but not vertical; depth may even be increased (but this may be an illusion created by the increased roundness and placement specificity of an image). A slight truncation of the deepest bass, with an increased weight of the upper bass; this was not noticed with the tube power amp.
The manufacturer was very considerate to send a replacement after the first one had some minor problems, so although this must be purchased from Malaysia, such a purchase can be trusted. Shipping was air mail and quick also.
Having been an audiophile for going on thirty years, this unit, a TVC, along with the discovery of single fullrange speaker drivers have set me on a new path from which I can't turn back. With the Promitheus, I can listen intently for longer periods.