Does anyone have any ideas what this little beauty is?...
I'm totally stumped...

TheMix Office  Suggested by jerseygirl 

Some version of TheMix. Probably Office, but I am not sure.

That's absolutely tremendous. Thank you so much for taking the time to help a dimwit in distress...

The client loves his new logo, too. Smiley faces all round.

You're welcome. Glad it worked out.