Any mention of Yes this summer has to address Chris Squire first. The legendary bass man was the only remaining original member of the band, but Squire's recent death from leukemia forces his colleagues to ride ever more changes. Yet even for a veteran unit well accustomed to dissension and departure, the loss of Squire seems unimaginable. Among bass guitarists and music heads in general, he is revered for his stupendous technique, feel and the feat of having introduced entirely new sonic hues to the instrument's palette. His virtuosic lines on "Heart of the Sunrise" and "The Fish (Shindleria Praemeturus)" are staggering — they not only anchor the arrangements, they blow them out into wild supernovas of rich texture and harmonic technicolor. But Yes presses on. Squire's close friend Billy Sherwood is subbing for his late buddy; we wish the very capable Sherwood the best in an unenviable role tonight at 7:30 p.m. at the Family Arena (2002 Arena Parkway, St. Charles; 314-896-4200 or www.familyarena.com). Tickets are $43 to $103.