Power an amp and component with batteries instead of direct outlet power?

I prefer to not change the batteries in my "stomp box" pedal board heap and have found serious low noise power supplies work fine. I have an old ac cabled MXR gizmo from the early 70s (I no longer use) that powered up to four devices using phone plug inputs. You bought these replacement back plates and put 'em on your MXR boxes and ran the phono plug cables to the power thing...there ya go. Used that thing for manny years. I've heard Johnson's claims and it fits his personality.

It's not a question if it works but if it will sell. That is always the answer to "Why not do..."

I use batteries for my DIY preamp and phono, which are just a few mA. But amplifiers need current, and so the required batteries get prohibitive - and dangerous - and generally not worth it. To me. YMMV

Living Voice uses a maga buck battery/inverter system when demoing their Vox Olympians. ok million dollar system but it can be done easily if you know much about batteries and charging cycles. just a few lead acid car batteries could power a system for hours if done right. hell you could potentially charge them using solar. or buy the Lio as mentioned above.