iPod docks and line-out

Q: I wonder if you can suggest a nice, small dock that can charge, sync and have fixed, not variable, line out for my third-generation iPod touch? I read the review of the dock for the iPhone but I’m not sure if it works with my iPod touch. As far as I know, the Apple Universal Dock doesn’t have a true (fixed volume) line out.

– Tran

A: The line-out on the Apple Universal Dock is actually only attenuated to reduce the volume as necessary and not amplified or otherwise modified in any way, so in that sense it is still a “true” line out in that it’s not passing through any audio amplification circuits.

This is done to allow the volume control on the iPod itself to match the volume being output from the Dock, however when the iPod is set to maximum volume, the Dock is essentially passing unmodified through the audio output.

That said, since the ability to match the volume control to the device itself actually requires the use of an Apple authentication chip, the Apple Universal Docks are some of the very few basic docks that provide any kind of audio attenuation. Even Apple’s own iPhone Dock does not support this capability, although it is designed for the physical dimensions of the iPhone and therefore not compatible with the iPod touch, at least not without physically modifying the dock to fit the iPod touch.

More sophisticated docks that include remote controls and other capabilities still often provide their own audio amplifier/attenuator, however, rather than a pure line-out, so you will want to stay away from any of the higher-end docks. That said, these usually carry higher price tags as well.

Another option that might be worth considering is to look for older Apple docks from other sources.