I do not have an iPod either, but your comments of typical gear are incorrect.
Typically, line-level outputs have a source impedance of 150 ohms. Speaker-level outputs are obviously much lower, many around 2 ohms. Line-level inputs are typically 10-15kohms, sometimes as high as 50kohms.
Impedance matching is only valuable for maximum power transfer. This was a requirement for very old systems that were power-based.
Today, virtually all audio circuits are voltage based. A low source impedance and high input impedance permits bridging (one source to multiple inputs) without overdriving the source.
So a low-impedance to high-impedance circuit does not distort the waveform. If the input is a lower impedance than the output then it could lead to distortion because it's drawing more current (basically overdriving the output circuit.)
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I do not have an iPod either, but your comments of typical gear are incorrect. Typically, line-level outputs have a source impedance of 150 ohms. Speaker-level outputs are obviously much lower, many around 2 ohms. Line-level inputs are typically 10-15kohms, sometimes as high as 50kohms. Impedance matching is only valuable for maximum power transfer. This was a requirement for very old systems that were power-based. Today, virtually all audio circuits are voltage based. A low source impedance and high input impedance permits bridging (one source to multiple inputs) without overdriving the source. So a low-impedance to high-impedance circuit does not distort the waveform. If the input is a lower impedance than the output then it could lead to distortion because it's drawing more current (basically overdriving the output circuit.)