Thank you all for your suggestions. I ended up using a triple surgeon's knot to make a loop-to-loop connection. I fished it this morning on the Yak and got skunked :( but the connection seemed to move through the guides fine when I tested it out.
Hi friends. I recently purchased a new 5wt fly line, reel, and backing, since my former reel became a victim of vehicle prowl. The fly line I bought has a welded loop on both ends, one to attach to the backing and one to attach to a leader. I have never encountered a welded loop on the back end...