Goals from Ross Hay, Sean Donaldson and Sean Beattie put the cup holders a 3-0 first period lead.
Sharks lost Gordon Horne through injury, stretching them further and the Caps twisted the knife as Callum Boyd struck twice along with Mark Patterson, Hay and Donaldson.
As Sharks began to tire in the third period, Edinburgh got the job finished with Patterson scoring his second, one from Joel Gautschi and Donaldson completing his hat-trick.
The second leg will take place next Sunday, at Dumfries Ice Arena face off 5pm.
ABERDEEN LYNX continued their pre-season preparations and did well against NIHL side Billingham Stars, even if they did end up losing 8-6.
Stars were 4-0 up after the first period, with Lynx fans fearing the worst, but they started to turn things around as Aaron Thomson and Ross Goddard found the net.
Although they were 5-2 down going into the final 20, Barry Carnegie’s side continued their resurgence.
Further goals from Jamie Vincent, Christian Johnston, Craig Johnstone and Mark Laing drew the SNL level at 6-6, but late goals from Chris Sykes and James Moss sealed a Stars win.
IT was a night to forget for SNL champions Kirkcaldy Kestrels as they were crushed 8-0 by NIHL Moralee Conference side Whitley Warriors at Fife Ice Arena.
Warriors were 4-0 up after the first 20 minutes with strikes from Jamie Tinsley, Martin Crammond, Kyle Hindmarsh-Ross and Callum Watson.
But David Longstaff’s side continued and completed the rout with further goals from Craig Johnson, Callum Queenan, Alex Lawson and a second from Watson to finish the night.