I use prewounds. Connecting Threads has great deals on them. Plus, I just bought a whole bunch of Superior and Glide prewounds to try while I was at the Houston show. I usually use muslin backings on my quilts, or neutral colors for quilting, so I get bunches of neutrals (white, off-white, light grey). They do me just fine. My Voyager likes to have the cardboard sides removed. If you use prewounds, make sure to find out whether your machine likes the cardboard or not
