I just looked at the database. The highest ever was 135dB hit twice, one 134dB game, one 129dB game. There are a ton of 128dB games (like over 100, most of them seem to be SNES, which I'm guessing is the max).
135dB - http://nhl94online.com/html/box_score.php?gameid=15393 - 22-0 NSH vs. CHI in GDL XI (Plabax vs. dcicon), prob dcicon dropped, I think I remember that happen.
135dB - http://nhl94online.com/html/box_score.php?gameid=24688 - 18-2 ARI vs. PIT in GDL XIV (Plabax vs. Labs66)
134dB - http://nhl94online.com/html/box_score.php?gameid=26498 - 12-6 CGY vs. DET in Classic Spring 2016 (Plabax vs. Uncle Seth)
129dB - http://nhl94online.com/html/box_score.php?gameid=28396 - 10-3 BOS vs. CGY in Classic Fall 2016 (Plabax vs. Uncle Seth)
So, moral of the story is play Plabax, get killed, make history.