The XA1 can be used with the build-in microphone on the iPhone, on the original iPhone the build-in microphone sample rate is only 8kHz so the highest band is 3600Hz.

When using the Headset plug for input (required for the iPod Touch), you can use a headset with mic combination or a breakout cable with 2 audio outputs and a mic input.

Line input:

None of the devices support line input on the dock connector with the current software, but it is possible to connect a line signal to the mic input via a simple L-pad consisting of 2 resistors.

To calculate R2 for 40db gain reduction:

    -40 / 20 = -2

    10^-2 = 0.01

    150 / 0.01 = 15000 (15k)


XA1 input