Leonid and Friends do mostly Chicago covers, led by the bass player, who transcribes all the parts note for note and anchored by a very solid drummer. The level of musicianship is consistently outstanding for everyone involved.
I’ll admit it -- I never cared much for Chicago (and I still pretty much stick to the uptempo Chicago tunes) but these players have managed to win me over. They also sprinkle in covers by other bands.
These are far more than typical covers. It’s terrifically alive and engaging music.
Check them out on youtube.
A taste:
https://www.youtube.com/watch?v=tJzlHBN3BT4
Note: the guy singing here at the piano is actually the leader/main bass player.