I own the Herron VTSP-1/VTPH combination and I have heard the IO/Callisto combo in a friends system. While the Aesthetix units are fine performers, I never came home after hearing them with preamp envy. The Herrons's are easy to live with: They don't require NOS tubes to sound their best, don't run their tube hard, don't blow fuses on start up, don't double as space heaters, rarely if ever get noisey and take up limited shelf space.
Aesthetix Calypso and Herron VTSP 2
Both of these preamps are highly rated tube linestages with remotes. Has anyone had any experience with them that they can share? Thanks