Let's be frank; the iPhone speakers really aren't all that great. People need to plug the device in to be able to hear what is really happening, and having iPhone 4S cases over the device usually doesn't help the sound abilities. The V-Moda VAMP is a different kind of case that adds sound power to the iPhone at a steep cost.
"This isn't just a battery case, although it packs a 2200 mAh battery," according to TUAW.com. "It uses an audiophile-grade digital-to-analog converter (DAC) to extract the digital audio signal of the iPhone, and then runs it through a two-channel 150 mW amplifier (five times more powerful than that built into the iPhone) to bump up the signal."
There are also two audio processing modes to help give the phone what the company calls a "3-D soundstage" with better bass and treble to make sure the iPhone's sound is much better than it would be without the case.
While the device comes with a $650 price tag, these aren't standard phone cases. The product's website said it features a protective metal case and gives great battery life as well as adding to the sound of the phone.