I’m using the “Ritter QC Amp Base SHP” with power option for QC. Sure, it’s much more than just “power supply”, it’s a power amp solution nicely setup especially for QC. I like it… power, power, power, power in several meanings 
I’ve been using 12V3A power adaptor that is mainly for laptop computers.
These days, I and my friends started using USB PD(type C) 12V decoy cable + mobile battery or PD charger.
Notes
Decoy cable has positive center plug, you have to switch the polarity somehow.
Also, 12V is not officially supported on PD standards, some chargers like Anker products do not output 12V. You have to read the product notifications carefully before you buy.