Well; SM and me floated from the peach orchard to 61 on Saturday and it was fabulous... a few fish were rising to midges but we primarily soaked beadhead Quasi PT's under an indicator with awesome sucess.
We counted a few dozen sulphurs over the day; no fish rising to them.
If you are hooking snot choke up, too deep.
My observation after a zillion years fly fishing is that a lot of BEHAVIORAL DRIFT occurs in the weeks prior to the main Sulphur hatch... essentially the sulphur nymphs swim up into the water column, drift on the current and settle back to bottom.... My guess is that they are letting the current take them to an area more suitable for real emergence OR they are "practicing" their swim-up technique. Don't know for certain but the trout key in on this behavior readily.
A couple weeks ago on the Holston I had more rises to my white Palsa indicator than to the dry's I tried! Go figure?