good advice so far, also I would say it's critical to not use a gate to remove otherwise removeable hiss. So again knowing what kind of hiss, hum, etc., you are talking about. I got some excellent advice recently from Shep (Pantherairsoft) on here about the obsessive way he cleans up his signal chain (better cabling, power supplies etc) which I find has helped me approach gating in a more relaxed way. Again, really sorry if you are well up on all this and I am stating the bleeding obvious!