Knowing Dr. West and his attention to detail, I would assume that he would install a switch or an automatic on/off (based on a signal), if SoundLab’s longevity were effected by leaving them fully powered 100% of the time as he instructs.
Moreover, I’m sure that Dr. West’s understands the capabilities and durabilities of his speakers and that he would not want their premature failure any more than we do.
So, with that said, I’ve been a SoundLab owner for over 20-years and have left them powered the entire time without detrimental effects. However even still, I recognize that I suffer from audiophile nervosa and I must admit that leaving my speakers powered, has posed a tad bit of a concern from time to time, especially in the early years of my ownership.