"How does running the Wadia directly into the amp compare to the Calypso? I have that option with the PS Audio DAC, but have not tried it. Before the PS Audio DAC, I had a Wyred4Sound DAC 2 with a digital volume control and preferred a preamp with that particular system. It sound fine as long as the volume was above 30 or so if I remember correctly. I'd have to figure out how to incorporate a phono stage though."
You just have to try it. Results can vary, its more of a personal preference. I get good sound either way but I like my system more with my preamp.
"Richard Vandersteen mentioned that if I bi-amp the 5As that it's important that the amp modules driving each speaker share the same power transformer or else the crossovers, amps, or speakers could be damaged. Can't remember exactly which it is, but his warning had put it out of my mind at the time."
Not so much damaged, but poor sound quality. That's why I do a vertical biamp. There's no need for you to worry with your Theta. You can only do a vertical biamp with it. Couldn't mess it up if you wanted to. I believe he goes over it in the owners manual.