Thanks very posting - great cover! "25 or 6 to 4" is one of my all time 10 top songs ( I even like the "remake" Chicago did of the song in the 80s, though the original can't be beat).
Chicago and EWF are my 2 favorite bands. Chicago was the first live concert I went to in the mid-70s. I made the Chicago logo on a jeans jacket and wore it to the concert, I had that jacket for years. I first saw EWF live when they came to my college town in 1978.
As a DJ in college and after, during the late 70s/early 80s, I made sure every show I did had at least one EWF and one Chicago song (even if the station music director thought I was crazy).
I saw EWF again in Las Vegas in 2007. We did not know they were playing, but went to the same day ticket booth and got 2 tickets in the 2nd room center. Fantastic concert.
DW and I, along with one of our sons and his then girlfriend, when to see the Chicago-Earth Wind and Fire Tour in 2015 when it came to the east coast. Both groups were FANTASTIC - they started out with a joint set, then Chicago played, then EWF, and they finished with a joint set. DW and I barely sat down for the entire concert. And we educated our son and his girl friend, as they had heard many of the songs, or the melodies in other songs or raps, and did not realize they were that "old"
If they come near me again next year, I'm going to plan to go again...