In the beginning of the DVD world, I also did not have a sub, so I set my mains to "large." The only concern you may have is with volume settings. You may find yourself setting the volume levels higher so as to hear the quiet passages and then the mighty bass explosion. Had this happen on Apollo 13, it convinced me that I needed a subwoofer to spare my mains. Maybe go with one of the compression settings until you buy a sub, (just a thought).