I'm specifically thinking of using the CSP+ / Taboo to drive Zu Audio Superfly's, they are 16 ohm speakers.

I'm new to this, but I thought a doubling of Ohms would halve the power and 3 watts is at the min for the SuperFly's.

With a classic solid state amp the answer is pretty easy, 1/2 the power at 16 ohms than what you get at 8 ohms.  This is with the amp being a voltage source that can drive either 8 or 16 ohm load to within a fixed percentage of the fixed rail to rail voltages in the power supply.  The maximum output voltage is a constant and the output power varies inversely with the load (within a certain range).

With a tube amp its a little harder.  The tube amp acts more like a current source than a voltage source, and a 16 ohm load, being easier to drive, will allow the amp to develop more current up to and until you run into the peak to peak voltage output limit that is set by the power supply, output tube, and output transformer.  All that said, the easiest way to figure it out is to just measure it.  I don't have a Taboo, but I do have a tweaked Zen that uses the same output transformer as the Taboo.  On my amp, at 600 hz, I'm getting 6.3 vac out into an 8 ohm load just before clipping (5w) and I'm getting 8.2 vac out into 16 ohms (4.2w).  I would guess, based on these numbers, that the Taboo should do at least as well at 16 ohms, and possibly a little more.

Dan