I received my adapter today. It cost me £0.01 including delivery from China as I was given some sign up discount LOL
So it works perfectly with the 20W power bank that I bought for £20. Been running it for the last hour with no issues at all.
I also found that I have to disconnect it when not in use or it keeps draining the power bank even though the Syntakt is turned off.
Here’s the link:
TOPK Power Bank, 20W PD QC 3.0 USB C Fast Charging 10000mAh Portable Charger, 3A Quick Charge with LED Display PowerBank https://amzn.eu/d/fbpSyuh