Durability and expandability

Wavemaster MOBI Mini Speaker System black first I fully charged the Mobi into a USB charger. After connecting the sound was surprisingly good, but the fun was after about 5 minutes on my Xperia Arc S to end. The Wavemaster was no more of himself peep, even though the battery was fully charged. Now exchange or repair is called for. I hope an isolated case.
Its own charger not was. The audio connection cable is too short, annoying! I miss a longer cable with retractor, as it is known for. B. Notebook mice ago.
An expansion connector to connect a second Mobi and to listen to stereo, there is not unfortunately. The battery is quite small with 500mAh. As long as he keeps well at full volume? Unfortunately I could not try it.