What is the difference between QSS 4.1 and QSS?

QSS = Quintessential Surround System 4.1 means there are four speakers, and one subwoofer behind the shell of the hot tub. This sound system is the ultimate in immersive multi-sensory experience. Beachcomber's original QSS boasts two high quality speakers - again behind the shell of the hot tub.  Both are audio transducer technology.