The Senators, who won 4-3 in overtime Friday, swept the series and outshot the Avalanche 72-37 in the two games, including 40-18 Saturday.
"It exceeded my expectations of how good it was going to be," Karlsson said. "I think everybody feels the same. Even though it's a long trip and a hard trip and you're not feeling great for a few days, I think that it's all worth it in the end. If you ask anybody in that room, and in Colorado as well, we'd be more than pleased to come back and do this again."
WATCH: [All Avalanche vs. Senators highlights]
Hoffman's power-play goal at 13:23 of the third period gave Ottawa a 4-3 lead.
Stockholm native Johnny Oduya and Mark Stone scored for the Senators. Stone, who scored two goals Friday, including the overtime winner, has nine goals in the past nine games.