I recently recorded a live vocal recital in which several people sang pop-tunes with a hand held mic. I recorded one track direct from the P.A. but unfortunately that track had a ground loop hum. What I'd love to do is copy a small portion of the hum by itslef, invert the phase, clone it several times then sum the tracks to cancel the hum on the entire track but to do this it seems I would need to position the cloned region with single sample accuracy to achieve the best phase canceling. I'd love to know how to select a region then perhaps use the arrow keys to nudge it forward or backward to get the right postion. Right now I only seem to be able to drag reagions and they seem to lock to a positioning grid. Any suggestions? Thanks, Stuart-