WOW, thanks for the answer. The main reason why i do this question about youtube quality is because i want to buy an HE400i, but i question myself if would it be worth buying those headphones if i only will play music from Youtube, or if with a $100 hp i will get the same sound quality because of the Youtube limitations. What i want is being alone in my PC, get the volume up, smoke a porro (yea, im from Uruguay) and feel my music, get the goosebumps that i had when i first listen to these songs, and it works better while seeing the MV, so i will not listen to 320kbps or FLAC/WAV, i will listen from Youtube.
The thing is though YouTube detail limitations isn't the only problem, as discussed above. But I wouldn't really advise going all out on the headphone either since one limitation could be, beyond YouTube alone, that your music might not have been recorded with spatial information in the first place, so the main benefit isn't going to be there. And live performances, save for classical/opera and some modern musicals (although not recorded live, they're just meant to follow the sound around like how the characters move on stage, like the original Phantom of the Opera and CATS! recordings, since these are the same audio for the video format release back when nearly all home video copies were also in stereo), tend to not have even less of that.
Anyways, probably i like more the HE400i. Plus, they are cheaper, and have less impedance. I don´t really care that much about the bass, what i like about the HE400i is the sound signature, the airy sound, the neutral decent bass (im not a basshead), good mids and nice clarity treble, i want the opposite to MUDDY sound
Here's the thing though: impedance isn't the only determinant in how easy a headphone is to drive. A 300ohm, 97dB/1mW headphone requires less than half the power that a 35ohm, 93dB/1mW headphone would, since every 3dB additional volume you need to double the current input power. Impedance comes in in two ways: some (usually cheaper) amps tend to have trouble delivering 256mW to 300ohms, but then again, chances are they'd have trouble delivering 512mW to 32ohms to begin with. This is like the difference between being able to power a Lotus Super Seven with a Ford 2.0L 4cyl and get 0-60mph in 4.5seconds, although given it has the aerodynamics of a brick, it can't go past 138ph (not to mention that engine barely has over 150hp) whereas a 3800lb Lamborghini Diablo VT with a full leather interior and an aftermarket sound system needs a 520hp 6.0L V12 to do 0-60mph in 4.0 seconds, albeit all that power and an extra gear plus proper aerodynamics allows it to hit 200mph.
The other way impedance comes into play is when whatever amp circuit you plug it into has a high output impedance. As much as planars don't suffer as badly from that as dynamic headphones that require, generally, a 1:8 ratio (ie load nominal impedance needs to be 8x higher than the output impedance), if you have a 30ohm output impedance with a 35ohm (or 22ohm load in the case of the HE400S) hooked up, it can still potentially make for muddy bass, regardless of whether it's because it's boosting the bass or even trimming it. As a more severe example the K701 can sound like a tin can on some OTL tube amps due to the 120ohm output impedance, but despite sounding like a tin can ie no bass, what bass is there sounds a lot less like
dum-dadum-da-dadadadadada-da-daduuum and more like
dwwuwwuwuwuwuwuwuwuwuwuwuwuwuwuwuwuwuwuwuwuwuwummmmmmmmmmmm.
So in short, if your problem is you can't send things back, might as well get a 150ohm, 97dB headphone like the HD58X. Although the drop is now closed.
Aren´t the HD 6XX harder to AMP? I dont think my Asus Xonar DGX have enough power.
HD6XX is 300ohms, 98dB/1mW. Needs around 175mW, but the amp needs to produce ~175mW at 300ohms.
HD600 is 300ohms, 97dB/1mW. Needs around 215mW, but the map needs to produce ~215mW at 300ohms.
HD58X is 150ohms, 97dB/1mW. Needs around 215mW, but amp needs to produce ~215mW at 150ohms.
HE400/400i/4XX is 35 ohms, 93dB/1mW. Needs around 512mW, but the amp needs to produce ~512mW at 35ohms, and to be safe, have around 10ohm output impedance, max.
Asus doesn't even release specs for the DGX headphone amp, claims to have 3 gain modes but calls them something else (High Gain is "Pro Gamer Mode" like actual pros are more likely to use an HD650 with small imaging than a K7XX) but also with some blurb about "amplifying everything even low sounds" (sic) which suggests that either Marketing wrote this with zero understanding of how it works or they understand that it quashed dynamics too (not that high gain by itself does that, but this card does) but they want to make it sound like it's a good thing (it's like Night Mode on HT receivers). Somebody just asked them and it got floated around the forum that it has a 30ohm output impedance.
Just on output impedance alone, the HD6XX/650 and HD600 at least won't have the output impedance issue. Next to that is the HD58X.
Even if we look past that, given it's not like the new Sound Blaster X AE-5 with 1000mW at 32ohms much less an amp with a fat power transformers surrounded by fat capacitors, I'd doubt it can do 512mW at 32ohms, so even if it might be too much to hope it can do close to 175mW at 300ohms (or 2V), even ~64mW at 150ohms is still a lot to work with on the HD58X (at roughly the same output level on the HE4xx series it needs double that still, just at 32ohms or so).
Basically, either way your DGX is more likely to not have enough power, but the HD6XX is relatively easy to drive vs the HE4xx, savings for which can more likely end up going to an amp anyway. As a compromise for both output impedance and power requirement there's the HD58X, more so if you don't need the bass plateau on the HD6XX anyway.
