Q: I would like to know what the difference is between PocketDock’s line out and the Apple official Universal Dock’s line out port. I found some articles that talked about not being able to adjust the volume when using line out, but the Apple Universal Dock with the remote control can do this. My thought is that if we use the PocketDock we would need to add an amp, but by using the Apple Universal Dock we can adjust the volume using the remote control without needing an amplifier.
A: Although you are correct that the Apple Universal Dock (iLounge rating: B+) will allow you to adjust the volume by using the remote control, it does not offer any kind of amplification capability. Basically, the Universal Dock has an attenuator contained in it to allow you to lower the iPod volume, but you will not be able to increase the volume beyond what the iPod line-out would normally be capable of.
Essentially, this means that the maximum volume level is the same whether you are sending the line-out through the PocketDock, Apple Universal Dock, or any other standard dock with line-out capabilities.
For most speakers, this will likely not produce sufficient volume, and therefore an amplifier would still be somewhat necessary. The advantage, of course, is that you can leave the amplifier at a fixed volume setting and use the Universal Dock and Apple Remote Control to adjust the volume, which may save some effort depending upon your particular configuration.
The one other slight advantage of the Apple Universal Dock is that the volume control on the iPod itself can also be used to adjust the output volume. The volume adjustments themselves are still performed by the Apple Universal Dock, but it is able to read the volume setting from the iPod and adjust itself accordingly. This can be advantageous when switching between different listening conditions (ie, headphones to speakers), since the last volume setting used on the iPod is retained when connecting it to the Universal Dock.