I have run some tests with my klingon D7 and federation Constitution. Both have more or less the same build, but the ToS disruptors from K13 just dont perform like they should be doing. I suspect that they are possibly dealing phaser damage instead of disruptor damage.
Furthermore, when you use beam overload with the K13 disruptor beam arrays, the beams change from the normal green, to orange/red in color. Here are screens of it.
Normal
Overload