Isn't a must however a good "recommendation". If not the you could have bursts of power and cut outs. Me personally I only use an adapter to charge if I can't solder it the lhs can and charges me 2 quid per item. 1.50 if I supply connectors. I'd advise against all use of adapters to be honest it's another solder joint to fail and tbh it is normally the adapter solder joints that fail.