We each have our definition fo single driver. To me, as long as it is used to produce sound from...ohh say 60-70 HZ to ohhh say 12-15 KCPS, it is single driver. It really is unreasonable (and in my miond too compromising from an engg perspective) to expect a drive to do the ENTIRE audible spectrum perfectly....it just ain;t gonna happen without major compromises.