Although I already listed some options for getting line-level audio into an iPhone or iPod touch, that list didn’t include much information that would suggest which option would be best. One important metric that people frequency ask about is frequency response. Well, I finally have some frequency response comparisons available to help answer that question.
These measurements were made of various dock connector devices, attached to an iPhone 3GS. As in other frequency response measurements, the audio was routed through the iPhone, with a little help from SignalScope Pro. This means that each measurement includes the frequency response of the iPhone 3GS headphone output.
The tested devices include:
- Tunewear Stereo Sound Recorder for iPod
- Alesis ProTrack
- Griffin iTalk Pro
- MacAlly iVoice Pro
- Belkin TuneTalk Stereo
Based on these measurements, and the unreliable nature of the iTalk Pro, I would recommend the Tunewear Stereo Sound Recorder for iPod as the Line-input device of choice. However, if you need balanced input circuitry, adjustable gain, or phantom power, then the added cost of the Alesis ProTrack may be justified.
As indicated previously, the iVoice Pro may still be the best option for the original iPod touch, depending on your needs.