Well last Thursday night I had the chance to witness someone sing NON STOP KARAOKE for 39 hours. At 1AM he sang his last song and you could hardly hear him , he was singing through what appeared to be a small consumer grade alll in one karake system . His voice was scratchy as I imagine it would be after 39 hours.
( I THINK HE ACTUALLY TOOK A 1 HOUR BREAK all in accordance with the rules).
It was for a worthy cause ( donations for cancer) and he had his family there cheering him on , the local news crew was there doing a story the day before and the owner of the bar was "proud" the place made the news. The owner requested that MY show stop a t 1am and asked all the patrons in the bar to go OUT to the patio and applaud this kid for his accomplishment. SO I'll have to wait and see if it shows up somewhere on the net as a world record.