So a couple of hours with the spot welder and soldering iron and the 6S beast is alive. A quick Youtube search for Woocommerce buying options add-ons has resulted in battery pack options for the ‘Sounds & Charge’ PiigBoxes.
There’s only one thing to remember. You’re still getting a 12 cell power pack with the same high capacity, but in your choice of voltage. The advantage of the higher voltage packs is the boost the bluetooth amp will get – so if you really want it to annoy your neighbours, go for the 6S option.