Originally Posted by amir_j
Just tried the iPod classic 7g eq settings while listening to it via a fiio lod and a portable amp. My understanding was that LOD would bypass any ipod internals but is not the case, the eq settings effect the sound produced by the line out i.e. choosing bass boost, vocal boot, treble boost etc all clearly cause a change.
Is this supposed to be the case??
Originally Posted by NA Blur
I think the LOD connection to the iPod is not truly digital and thus has some analog component to its signal. This explains why you receive some effects from EQ. If my memory serves the digital out from an iPod is encrypted and the only easy way to get at is via LOD is use filtering caps to remove the analog signal. This is why I still claim that I cannot hear the difference from most LOD connectors compared to the headphone jack out.
If you are using an LOD into an amplifier, you are bypassing some of its analog circuits. Even if you are using an iPod DAC like the CLAS with a 30-pin to USB cable, you are still not bypassing the EQ, depending on the software implementation. Why? Because forget your Dad's stereo from the 1970s and prior with a separate EQ box, or your car system from the 90s with an Audiocontrol EQ after the receiver which uses a CD changer - EQ is now usually implemented at the software level. It doesn't matter if it's a computer, a tablet/phone player app with EQ, a DAP, or even a car audio receiver - you cannot totally bypass the processing unless it has some kind of EQ-off/Direct Mode (as opposed to Flat, which is sometimes the same thing, but not always) since many devices incorporate the DSP and DAC into the same chip (ditto car audio receivers and processors - they are basically HT receivers with different settings to optimize two channel audio instead of surround), or as with DAPs and multi-purpose devices, even with dedicated DAC chips the processing can be implemented prior to the decoding or digital streaming out of the device.
The only hardware EQs nowadays is the bass boost function on amplifiers.