I’ve been using a Rane Sm-82, 8 stereo channels, and a two in two out stereo effects return. I bought it off E-bay. A more affordable option is a Euro rack mixer from behringer. They make a one rack space model that is similar to the rane but actually has a headphone out which the Rane does not. I’m very happy with the rane, though I’d like to get it modded like David Torns to have two independent effects sends.