I definitely noticed a lot of hiss if there was anything active in the Stack section but CK told me it isn’t designed to use in conjunction with anything in the Stack. As soon as I turned the stack off I got no hiss.
CK also recommendeds using the AC Sim in slot X after the Atack as it runs in sterwo there with a space effect automatically added. I find I prefer it in the Stomps in Mono as the space effect sounds too much like a double tracking effect to me so far. Maybe it will grow on me with some experimatin though 😆