You can put it between the amp and pre-amp - pre-out to C-9 in > C9 out to amp. I'd prefer the tape loop initially at least just to confirm to your self that it is both effective and desirable in your set up by switching it in and out. I found that when I took great care in setting up my listening position and speaker location properly I really didn't gain much with the C-9. And the C-9 instructions specify a good triangulated set up to work properly so you are half way there. If you have to put your speakers close to a wall however you might like its effect, or not. FWIW.
Help with proper hook up
Can anyone please help me hook up a Carver C-9 sonic hologram generator? I have a Cary V12R tube amp and a Cary SLP98P preamp. The carver unit has left and right IN and left and right OUT on the rear. I have 2 sets of main outs on the preamp. A Sony CD recorder is hooked up to the tape loop on the preamp. Thanks polk432