Mac-Mini --- Dac Magic ----Toslink because thats all that will work
SB3 ---- Overture ----- Toslink because thats all that will work
Netbook ------ Pico ----- USB because thats all that will work
Transporter ------ CA 840c ------ Coax RCA because I can
I let the majority carry my poll vote
You also may want to consider that those tubes match well with the Esoteric as source. I'm pretty sure that you don't want to extrapolate to other sources as the esoteric units I have heard have a definite "house sound".