I’ve been playing around with a Power Chorus that I assume is similar to the Princeton Chorus. The mono effects loop comes out between the preamp and the chorus, so you can use that and still have stereo effects after. I think the stereo loop comes out post-chorus, but it does drive the speakers separately (stereo power amp). The TRS cables I have aren’t great, and I’m getting tons of noise and a radio station when I try to figure it out. Based on the manual, the stereo send and return maybe isn’t really supposed to be a loop. All the suggested setups use the send to pass a stereo signal to a desk/pa, or to second Power/Princeton Chorus, as a slave, going into the stereo return.