Here is the power bank I used: TalentCell Lithium ion Battery Pack NB7102, Rechargeable 17500mAh 64.75Wh Li-ion Power Bank with DC 24/19/5V and USB-C 5/9/12/15/20V Output for Laptop, Notebook, Smartphone, Camera and More a.co/d/7lGVaT8
I was going to buy this some years back but was put off by the fact it had no Mic channel, why they left out a Mic input beats me, most buskers sing and play. In the end settled for a boss cube street amp. It must be light the amp otherwise it may cause some back problems especially to older people? I bought the spark go for practice and playing in archways and tunnels but if they bring out a buskers one with Mic input who knows.
Having a mic input would be great, but I think they are trying to keep the Spark 40/2 as a practice amp and are pushing the Spark Live as their live/busking rig as it includes multi-channel inputs and vocal processing as well.