Hi, all. I'm new here, but I thought I'd make a quick observation.
In "The Emissary," the Enterprise-D has a faceoff with the K't'inga-class T'Ong. They are clearly not concerned about the T'Ong's tactical abilities, and the Enterprise easily shrugs off the Klingon disruptor fire--twice.
In "Prophecy," Voyager is attacked by a D7 Klingon cruiser, which is even older than the K't'inga-class. The Klingon ship knocks Voyager's port shields down to 50% with a few shots.
So, the Enterprise decisively outmatches a 23rd century Klingon cruiser--the Enterprise crew knows it and the Klingons know it. Voyager trades fire with a 23rd century Klingon cruiser and does get the upper-hand, but it takes some significant damage to its shields.
Direct comparisons are hard, since both shows jumped around a lot with measurements of power. Data says the Enterprise generates 12.75 billion
gigawatts in "True Q". In "The Dauphin," Riker says that a terawatt source is "more power than our entire ship could generate." LaForge says the Enterprise "kicks plasma up into the terawatt range." There's a line in "Revulsion" that Voyager's main power supply has "5 million gigawatts" running through it. Through the whole TNG-VOY era, different power measurements are tossed around with very little consistency.