From a poster in "The Rush Forum":
Quite possibly the most underrated prog band from the '70s to mid-'80s. Most people know them from "Carry On Wayward Son" and "Dust In The Wind," but Kansas (on mainly their first five studio albums) belongs in the same category as Genesis and Yes for orchestral-sounding prog-rock. Kerry Livgren, who wrote most of their "deep, pondering" tunes, was equally adept at both lead guitar and keyboards, which when combined with Steve Walsh's searing organ playing and Richard Williams' "meatwall" heavy guitar, made the band sound both like a hard rock band and an art-rock prog band. Steve Walsh had an instantly recognizable voice, and he could sing his ass off. Having a full-time violinist in Robby Steinhardt also helped define their unique sound. In any one song they could go from a loud twin-guitar/organ attack to a soft piano/violin duet. Kansas was very diverse.
Growing up I was into Led Zep, Deep Purple, Ted Nugent, Aerosmith, Boston, and the whole southern rock thing. Then I heard Kansas' Leftoverture album, featuring a 6:41 instrumental (with a small vocal section thrown in) named "Magnum Opus." It featured tricky time changes and insane playing. I'd never heard anything like it, and that album introduced me to prog rock. A couple of years later Rush's Permanent Waves came out, and I haven't listened to Ted Nugent since.
A while back I linked to their prog-rock masterpiece "The Pinnacle." The same YouTube member also put up "Journey From Mariabronn," which was also played on the Don Kirsher show. Though, "The Pinnacle" was a more polished performance (given that "Journey" was played shortly into the band's career, "Pinnacle" was played on a subsequent Kirshner show, after the band had a few years of touring under its belt). I've embedded Journey from Mariabronn because it is, I think, one of the best written progressive rock songs. And Steve Walsh's voice is in its prime in the performance.
Now Walsh, unfortunately (despite being a fitness buff, who even now in his mid-50s can run 20 miles at a time), did a lot of drugs and alcohol and for a while didn't take care of his voice causing it to terribly deteriorate. For instance, see this performance of "Dust in the Wind" on their Live at the Whiskey video, which marked a low point for Walsh's voice.
As you can see, he can still carry a tune and phrase nicely, but he lost almost all of his smooth tone (and some of his range) which was what was so appealing about his voice. Then after being arrested a number of times, in his mid-40s (about 10 years ago) he cleaned up his act and rehabiliated much (but not all) of what he lost in his voice. From their 2002 DVD, entitled Device Voice Drum, here is "Carry on Wayward Son," where Walsh redeems his "hoarse" performance in Live at the Whiskey (not quite how he sounded in the 70s, but at times he gets close).