Headphone amps, external power supplies: what difference do they make?, was: "First post here, Hi." Options

[1096bimu]

Ever since I was told that it is possible to tell 320kbps CBR from loseless, I've had some interest in hi-fi, and that was a few years ago. Today, I use an ASUS Xonar Essance sound card and an AKG Q701 headphone. I am pretty confident that it sounds better than all the cheaper alternatives I've had before, and I am quite proud of my own ability to eliminate biases without blind testing (because of lack of equipment). However, 320kbps MP3 is still transparent to me. The absolute best I can do is tell 128kbps, and it is extremely difficult as I have to go through the samples multiple times to try and spot one or two obvious distortions, and tell from that. If I couldn't find any than they sound identical to me. I have read through many of the FAQs, compilation of test results and older posts so I know this isn't uncommon and isn't what I am worried about. I keep everything loseless even though I can't tell the difference because I don't have that many music, only a few gigs which isn't a problem for today's mobile devices (exported selected few from CD images).

The biggest problem is I keep running into this claim that headphone amps are supposed to make ginormous differences, especially with the AKG Q701. Some people say there is more difference with the K701 but aren't they identical except the colors? Of course nobody could show any blind test results and they are nothing more than testimonies. I am not a hard core audiophile I don't have any audiophile friends so it's not possible so it is not possible for me to try out stand alone amps. It just seems to me that many of these audiophiles believe in some kind of mystical superiority of external boxes. You gotta have an external DAC, and an external amp and you have to connect them together. I mean today they are just intergraded circuits why do they have to be external? The Xonar Essance says "Headphone amp card" and it does have an amplifier chip as well as those small ones that you can swap out and everything, so What's the difference?
In fact, I tried the Q701 on my cell phone, iPad, on-board intergraded audio, and even an iPod shuffle. They sound slightly worse I would say, the difference is quite subtle when compared to the Xonar. And I could not tell any difference between my phone, iPad and iPod shuffle.

I've also heard that you have to use an external power supply (it has a port that plugs into the computer power supply) for the Xonar to "bring out its full potential". Again, what's the difference? are computer power supplies not stabilized? I guess I also count as an overclocker so I know how voltages in the computer are set to two or three digits after the decimal, it is really sensitive stuff. I mean maybe the computer with its variable power requirement will destabilize the power source, but I don't listen to music while playing games or anything, I leave the computer idle for that. Also being a fairly high-end spec, the -12V power supply has a capacity of 650W (for 12V alone) , isn't that enough head room for small fluctuations?

[J.Philippe]

Doesn't the Essence card already have a headphone amp on it, as well as a dedicated power connector?