Old thread but current thoughts... I have had the Calypso and Rhea Signatures for a long, long time, tried most every band/type and find a 5751 RCA triple mica black plate to be the weapon of choice in my pre, with Amperex 6DJ8s. I utilize an NOS quad of Telefunken smooth plate 12AX7s (Amperex Bugle Boys were also very nice, perhaps offering just a bit of music sparkle (NOT overly tipped up at all)) in the first gain stage of the Rhea for their clean, top to bottom linearity and lack of added colour, and RCA 7058s (per Glenn at Aesthetix) in the 2nd stage (RIAA). The 3rd has far less influence on tone. I found a date matched pair of Telefunken 6DJ8 medical grade that are dead quiet (between the music of course) for the final sockets. Sounds lovely and very revealing.
