Suggestion: Use an external PC DAC. Don't double amp it. Sounds like the O2 is doing it's job just fine. It's supposed to not change the sound of what's connected to it. Sure maybe some minor improvements. With my O2 and Micro I can expect to connect up a 2Mb Coby Mp3 player and have it sound the same. I want to hear my source/music and not my amp.
 
With an external DAC the differences would be much greater.

To expect anything from the O2 amp when it's designed to spit out exactly what it has been fed is rather interesting to say the least. the O2 is known to be pretty much neutral, to some: boring, cold and analytical. I'm currently waiting for my output booster kit from AGDR, which from what I've read should nudge the amp into becomming a more musical little box. If you're interested on how it changes the sound for me, feel free to PM me or search for "O2 headamp output booster & modification PCB" on the DIY section.
If you want my honest opinion, an entry level "high end" laptop is around the $1000-$1400 mark, even then it may not guarantee a decent DAC inside, but from what I can see it may as well be a laptop which includes a built in headphone amp. Hard to say since Asus has the tendency to spec laptops for specific uses.
Perhaps we can gain a better understanding if we know which specific model you are using?

You are double amping... of course it will sound the same.

Even if he wasn't double amping, the dac is probably garbage anyway.

OK I edited my review in light of the helpful comments.

This is the specification of my laptop's headphone jack:
 
"The Class D amplifier is designed to drive speakers with as low as 4Ω impedance. Its maximum output power is 2.3W per channel at 5V power supply."

Do you have the amplifier built for 1x gain? If that's the case, then it won't amplify the signal at all. Try pressing the push button to the right of the volume knob and see if you get more volume.

P.S. I mainly got these because some people misled me into believing (despite what my ears told me) that my HD800s didn't sound as good as they could, because my phone/laptop couldn't drive them. Well apparently both my phone and laptop have decent amplifiers, so I think that's why this isn't doing anything for me.

if you can't return it, might as well invest in a good dac to improve source quality and do it the way its supposed to be.

and laptop jack are powerful these days. my laptop drives my headphones much louder than external usb powered dac/amp I own. but in sound quality there is no comparison. dac/amp is much better.

Yes. Apparently my laptop jack is strong enough to drive speakers.
 
I just discovered that I have a Realtek ALC269 DAC in the computer. Is that horrible? What's a good upgrade?

One other question, when you guys play your objective 2 amp -- what volume level do you set it at? I'm wondering if I should turn the volume of the computer to the max, and keep the volume of the amp low, or vice versa.

technically, the Realtek ALC269 is not a bad DAC chip, but most laptop manufacturers rarely implement the chip in a way that meets our expectations: even the most efficient power supply units in PC's provide noticeable noise within an audio setup, if your laptop has implemented its own power regulator for its DAC then that's a good thing, but it rarely meets the same specifications found in an external DAC unit.

For other DACs as upgrades, you cannot go wrong with an ODAC. Or if you want a small taster of externally powered USB DACS you could go for the cheap (but performs incredibly well) ELE DAC EL-D01, which unfortunately seems to be available in Ebay from China. I am only suggesting those because I have experience with them, but feel free to look further into the review and discussion threads here.
 
As for the volume I would suggest that you keep the volume at 100% on the computer, and use the volume controls on the Amp.

How can it sound any different than the headphone jack if it is merely amplifying what comes out of the headphone jack?  Please retry this test after using a dedicated DAC, and then compare the O2 versus other headphone amps.  Otherwise you have no comparison.  Can't understand why anyone hasn't bothered to state this explicitly....you are in no way comparing the headphone output of your laptop to the O2 because the output of the laptop is always on.  In fact, I find it amazing that you find the O2 that good in this setup.

"you are in no way comparing the headphone output of your laptop to the O2 because the output of the laptop is always on."
 
Wait, what do you mean by this? Do you mean to say that the O2, through some electronic signals, knows that the source is itself a powered headphone jack, and the O2 just steps aside and does nothing but control the volume? In other words, the power is coming from the laptop headphone jack and the O2 is basically acting as a wire?
 
 
JacobLee,
Thanks that ELE DAC is super cheap so it's worth a try. Out of curiosity, can you please recommend the best DAC that isn't priced in the crazy $500ish territory?

p.s. I would like a 24 bit 192khz dac if possible. I noticed that ODAC is only 96khz

I think you don't understand what is an amplifier. It doesm't do voodo magic. It takes an input signal, and outputs it with bigger amplitude. That's it. In your case, you are feeding with your computer headphone jack. So you are taking this signal, and making it bigger. This won't change sound quality. The thing is, if you invest in a good source, the amplifier will have something good to spit at the other end.

Side note, what gain setting were you using on the O2?

you don't need a 24/192 dac for 320kbps audio... impedance doesn't mean everything, a low impedance he6, im pretty sure you will want to amp it.

with a good amp, the hd800 is amazing. I had the opportunity to listen to it from a cheap amp, and it was eh. Through something more powerful, it is incredible. The HD800 scales well, but this is not the amp and you do not have the correct dac to do it justice. Look at other threads and you will see that others spend a minimum of $1500 for an amp and dac. You have a $1.5k pair of cans, so spend more on using them correctly kinda like Stax.

For note, an asus computer and a samsung phone are not high end media devices. $800 is not much in the audio world, and some DAPs cost more like A&K offerings.

This review should just be deleted