Both controls reduce the voltage across them, and are followed by circuitry with a fixed gain.
Best bet is to listen for yourself. First, set the tripath level control to maximum and use the Quickie to adjust level. You will probably hear a lot of microphonics from the quickie, and have a hair-trigger volume control.
Then reduce the tripath pot, increasing the Quickie control to compensate. The microphonics will decrease and the available range on the quickie pot will increase.
Keep trying lower and lower level at the tripath, until you hear distortion on loud passages. The ideal level for the tripath pot will be between these two points. By the time you find that optimum, you will have educated your ears - a really nice side benefit!
:^)