Good playrun in high levels, pleasant easy run when lower. Possible alternative putin at Newbridge if you want to shorten the trip.
Takeout in Rhayader, just downstream of the B4518 bridge on river right after Rhayader Falls. Takeout in Builth Wells: follow the one way system round to the carpark on river right just upstream of the A470 bridge.
Rainchasers is best experienced as an app.