I'm almost done building the 9-wt outfit I posted about a few weeks back; the only thing left to get is the fly line (running line + shooting head). I am going with RIO for this, and the running line I'm looking at has a welded loop on both ends, I believe. I also know that getting GSP line - like the 50lb Power Pro that I bought for backing - to hold a knot can be difficullt, so I thought I would ask: what is the best way to make a loop to loop connection between the running line and the backing?