I am glad that everyone is choosing to get along rather than flame each other!
I don't want to argue or anything, but I can say, "lets not be too quick to divide each other into camps - purists, and non-purists". I am all for using audio 'tools', for example, but that doesn't mean ALL of them. In a car audio environment some people think time alignment sounds worse (you loss some of the 'boom'). Many DSP features "like loudness" are useful at low volumes but interfere when the volume is going up etc. Listen to any OEM system in a car - they most always are too bassy at low volume, and bass-less at high volume because DSP/EQ is attempting to control distortion. That is what I consider poor implementation (significant audible changes throughout the volume range). I always use only what I think is really improving the sound, and everything else is turned off. I am very 'set it and forget it'.
There is no such thing as a 'purist' anyway, given that audio is processed at every single step of the music making process. Using none of the tools at your disposal only means you have left it to others to determine your listening enjoyment. And they have 'altered' the sound from the time they were tuning instruments, to the time they picked a recording venue, to the time they were tuning the recording, and so on. You then go out and get an amp and phones with a 'sonic signature' (i.e. imperfect replication of the audible spectrum) and listen to the end result on some digital medium that is compressed or not (and which may be clipped anyway). Thus even when attempting a 'straight wire' connection to your music, you are beholden to a number of factors well beyond your control. If you can't optimize speaker placement, or if you don't have a quiet listening environment, the tools you can use are typically a blessing, not a curse.
That said, adding 'noise' is a problem in any system. But especially in car audio, you can get away with higher levels of distortion and noise because nothing is noisier than the car you are in! My amp has some 'hiss' at high volumes, for example, but it is undetectable in 90% of listening. It still sounds better than lesser amps, and is compact and efficient. I only here hiss when the car is off and I am jacking the volume with nothing playing. So, maybe an issue at the drive-in, but never on the road.
Now to get real confusing: I consider myself a "purist". I always seek to simplify my audio chains to the maximum that I can, and seek minimum use of any sort of software or hardware alteration of my sound. IF eq tuning were creating too much noise, I most likely would do without. I once stuck foam over tweeters to try to quiet them down a little, rather than EQ them. There are lots of tricks at our disposal, not all of which are about the electronic space (hence the 100 pages about modding the earpads). But like others, I too try to buy the best sound I can right out of the box, because you do usually get what you pay for. There is no making crap sound awesome. But there is making Awesome sound like crap! I can still enjoy the HE-400s on there own, no mods necessary.