It will be similar to a Uni-Vibe in cancel mode, but without the frequency coloring from the LFO. In an Uni-Vibe the cancel function shuts off the bulb, but even in the dark the LDRs will color the sound. So I don't think you'll get that Jimi Uni-Vibe in cancel mode sound off the bat with just the preamp.
Just my 2 cents.