The Edinburgh side travelled to Rubislaw top of the table with the hosts bottom, so an away triumph seemed likely, but they really turned on the style.
Charlie Brett, Gregor Hunter, Adam Hall and Rhys Davies bagged tries in the first half to give the Malleny Park men a four try bonus.
Wallace Nelson, Cairn Ramsay and Ryan Southern added further scores before the break and it was 47-0 at half-time.
Ryan Stewart scored early in the second half before the one score of the day came from Grammar.
Nelson, Southern and Ramsay all scored their second tries before Davies did the same and Hamish Ferguson finished the rout.
Second placed Marr were also winning away from home, though their game was a bit of a tighter affair.
They came out on top 28-17 at Musselburgh.
Third placed Edinburgh Accies made sure of a play-off place with a win.
Accies great home form this term continued as they saw off Selkirk 24-9 at Raeburn Place while Hawick are all but confirmed as being in the play-offs too.
The fourth placed Greens won 34-10 at Jed-Forest while fifth placed Hawks, who now need something of a miracle to make top four, lost 20-7 at home to GHA.
Meanwhile, tributes have been paid to Watsonians secretary Iain ‘Stavvy’ Leslie who has passed away aged 59.
He was involved in many roles for the Myreside club for 42 years and they held a minute of applause before their first XV game versus Highland yesterday.