Hey,
Don't think it's Pirin street the Bansko is on. It is right next to the Mura. To get to it, coming down from the Gondola, when you get to the Lion pub take the road on your left that's next to the river and it's about a 5/10 min walk. We stayed in the Mura but used the pool in the Bansko which was really nice and it seemed like a nice hotel. Also not far from the centre, just need to take a road on the right and it takes you straight to the town square.