Bought this to use with a wah-wah pedal, but it creates a terrible high-pitch background noise together with that pedal. Not suitable for the intended use!
When I run the pedal on battery instead (adapter not connected) the noise is completely gone. Tested another "branded" adapter, and that had just a very low and acceptable hiss. Components in the signal chain (guitar, cables, pedal, and amplifier) of very good quality.