‘VentureCraft’ is a Japanese company present at CES with their new clip-on unit for the iPhone. The reason that you may not be familiar with the name is they are fairly new in the arena, but they have managed to build a unit that works as a rechargeable battery, and also serves as a headphone amplifier to strengthen the output audio on your favorite iDevices – iPhone 3GS or iPhone 4.
While the current GoDAP model (developed for iPhone 3GS) is already available on the market, it is not as impressive as the new model which will be thinner and ready to ship in April. This unit has a digital audio output, which can be sent through an optical cable at either 96k / 24bit or 48k sampling rate. What this means is that you can use your DAC port to send audio to a home theater system directly from the iPhone itself, and because the amplifier is running it is going to sound much better. The frequency response is listed as 10Hz to 120 kHz and the relative headphone impedance is listed as 16 to 100 ohms.
Looking at the price, the 3GS version (without optical attachments) costs $199 shipped from Japan, whereas the new model (for the iPhone 4) will cost around $300-350, shipped from Japan.