I just purchased a set of XL Half rounds and put them on my new Super J 5 string active/passive bass. I had a set of flat wounds and I didn't notice any lack of sustain. I tried bending the string at the bridge and the nut to give it more angle. That worked some but still not where I would want it. The other 4 strings are fine. Could it be the string itself or because they are half wounds? I admit I only have about 1 1/2 turns on the tuner post. Any advise would be appreciated.