For those of you who use A/B pedals. How much hum do you notice when you use an A/B pedal? i.e. compared to how quiet the amp is without the a/b pedal plugged in, how much hum do you find once you plug the a/b pedal in. I've heard that a little hum is usually introduced on amps when you hook up an A/B pedal, and that the amount of hum you get varies from amp to amp. I certainly do notice this as well on my /13 RSA 23..if I hook up an a/b pedal I get some hum if I jack the click channel volume up half way or more. Please share your experience with me...it will help me as I work with Simon to decide direction on a few things. Thanks much.