Are External Preamps Worth Buying? (Stock Preamps vs. External Preamps)

Quick timestamps:
Acoustic - Stock Preamp - 1:20
Acoustic - External Preamp - 1:56
Acoustic - External Preamp (more coloration) - 2:32
Ambient guitar - Stock Preamp - 3:08
Ambient guitar - External Preamp - 3:46
Ambient guitar - External Preamp (more coloration) - 4:24

In this video, I am testing the stock preamp from my audio interface (Focusrite Scarlett 6i6) vs. external pre-amps (Golden Age Project Pre-73).

I want to demonstrate what is the difference in tone between pre-amps so you can decide if you need or not to spend money on external pre-amps.

This video is more targetted for guitar players, as the examples are only on acoustic and ambient electric guitar.