Hardware is hard. Power supplies are hard. Audio is hard. In that order. Charger 14.5V x 3.3A = 47.85 Watts maximum rated power output under ideal condition

Hardware is hard. Power supplies are hard. Audio is hard. In that order. Charger 14.5V x 3.3A = 47.85 Watts maximum rated power output under ideal conditions. It's the law. Ohms law. Barrel connector looks like a laptop one, this could be even more of a bottleneck compared to the limited power of the charger. The physical point-contacts are so limited it can only pass so much amperage. Higher amounts of power usually require higher voltages than 14.4V unless beefier connectors are used, which allows more power (at the same maximum amperage) to be conducted through thinner copper wiring and lower-cost connectors. It would be good to know the specs of the audio output amplifier and speaker assembly but chances are it takes a lot more than 47.85 watts of audio power output to get 126 dB from the speakers. More like 100W RMS delivered to the speakers as an estimate. You can't get more out than you put in, plus significant energy efficiency is lost in places. And that power would have to come from the battery if the recharging connector was not a strong enough source. Ideally there would at least be adequately beefy fully-soldered wiring & connections between the battery and audio output circuit, to supply it with the fully rated input power unless a lower engineering target had been designed. So it seems to be full performance as issued was only ever within reach under battery power so it is basically a battery-powered speaker and the charger as it says on the device is merely a "battery charger" not an A/C line source for highest-performance operation. Imagine if you will, you are running quite loud and drawing the maximum rated power from the battery pack, if this just happens to be 99.84W of power, the batteries will last only one hour like it says on the battery pack, 99.84Wh. So the most you can get is one hour if you're drawing close to 100W, and the audio output will still be measurably less than that. Once the battery is discharged, the charging circuit including the external charger may or may not be intended to continue powering the speaker, but it could not realistically be expected to get very near full output dB performance.