edsherlingmd@yahoo.com writes:
The iPod uses a cruddy, standard Wolffson Microelectronics low-power DAC;
The iPod has always used a Wolfson Microelectronics DAC. The first and second generation iPods - WM8721; third generation - WM8731L. Fourth generation - WM8975 CODEC; fifth generation - WM8758 Audio codec. Some think the WM8975 is the best sounding of these.
As some know, Arcam changed from the dCS "Ring" DAC to a Wolfson DAC. Obviously there were many business reasons involved in this, but Arcam are a savvy company with a good reputation for sound quality, and Arcam chose to use chips from this Scottish DAC manufacturere. For example, the Arcam CD33 uses the WM8740 DACs, and it's a good sounding player (though I prefer the earlier "Ring" DAC).
I'm not saying the WM8975 is a great DAC. I just don't think it's "cruddy".
headphone amplification is handled by the same chip. It is built into the ipod, rather than the dock, unfortunately.
No. The headphone amplifier is handled by an opamp output stage following the Wolfson DAC. This can be bypassed as Red Wine Audio do with their iMod.
We take the analog output (line out) off of the dac chip and send it directly to the internal 1/8" headphone jack (converting it into a dedicated line-out jack) via high-end Black Gate Non-Polarized NX-Hi-Q coupling capacitors
The pin outs have been published. See
http://pinouts.ru/Devices/ipod_pinout.shtml.
There is digital data coming out of the iPod on both the Firewire and USB outputs. But it's not in SPDIF and you can't feed it to an external DAC. The MSB modification extracts the digital data higher up in the chain and run it through custom circuitry, as shown on their web site. This is a $2000 "mod" as you cannot get the $200 iPod mod without buying the system.
Regards,