I love when i listen to established band who had to experiment with current sounds to stay relevant,and i don't think of the music of today.

I just loved when Chic abanndon their disco sound in

favor of new wave and Nile Rogers

started played guitar solos on his records.

i love when Rolling Stones were a punk new wave influenced it

refreahed their usual style:

http://www.youtube.com/watch?v=r6-twZlxt_k

do you like when your favorite musicians and bend sometimes sounded totaly different out of their comfort zone

or were you angry when you heard your favorite hard rock(Kiss ) band playing disco ?

My two favourite bands are Pink Floyd and Guns 'n' Roses.

I wasn't around for the Floyd changes in style, but I much prefer their 70's output over the psychedelia of the Syd Barrett era..."I've got a bike, you can rid it if you like", no thanks, too village hall for my tastes. Anything from Echoes onwards, amazing stuff. I guess you could call the post Roger Waters era a change in sound, and I love the two albums they did without him, very underrated in my opinion.

The Gunners haven't had too many drastic sounds changes either. Appetite to Illusion I guess you could say that they went from a raw/punky sound to a fuller, more studio produced sound. Both worked for me, so I wasn't too bothered. The biggest change would be the "old" Gunners versus the "new" Gunners, and I really wasn't taken with Chinese Democracy, not enough stand out songs and it was too uneven.

Most of my other fave bands (Foos, Killers) haven't really had massive changes in sound...yet. With the exception of the Smashing Pumpkins, but that's part of the bands appeal, you never know what they are going to do from one album to the next!

Cameo. From bigband/horns-sound (1976-1981) to newwave-synthfunk (1982-...).

I'm usually pretty unimpressed when a band changes its sound, or when something happens to the chemistry:

Guns N Roses - Use Your Illusion - suddenly this group of desperate punks get shitloads of money and praise, they think they need to be serious and "important"

Smashing Pumpkins - Mellon Collie - Billy was swallowed by his ego

Prince - Lovesexy - He forgot how to be funky

Van Halen - 5150 - Finally rid of that asshole David Lee Roth, unfortunately they didn't recognize that he was at least 50% of what made them awesome

The most noticeable change in any of the bands I like was undergone by the Doobie Brothers.