Right now I'm using a HD 650 paired with a Essence ST. I've been reading around on some other peoples setups and noticed some people choose to use an external AMP. One of the guys I read is using a little dot MKV. What is the purpose of this exactly considering there is an in-built headphone AMP on the board itself. I'm not much of an audio guru but I can definitely appreciate quality sound but from my understanding an amplifier just increases the output power, not the quality. The quality itself should be handled by the headphones and the soundcard drivers. I couldn't imagine someone actually using higher volume then what the in-built AMP already provides without blowing his eardrums.
The reason to use a external headphone amp, over the one that built into a sound card. Is to supply power to the headphones, If the sound card in-graded headphone amp IC is not strong enough to do it, or is sending enough voltage to it. It has nothing to do with making it louder, even if the headphone benefit from a hp amp and you plug it into a sound card without a amp, Even if it gets it loud, it still not doing justice for the headphone. Thats why you don't use a hp that need a amp to shine un amp even if it gets loud enough, because it still not getting the power it need to shine. Using a headphone amp has nothing to do with making it louder, Its all about giving the headphones that a stronger amp, more power so they will output at there fullest instead of half way or almost. Then some headphones can be amp picky as well. Also the STX and ST RCA output's path that's on the sound card is better then their headphone amp output's, so some people also get a external amp to use the RCA out of the sound card. Sure you could plug a headphone that benefit from being amp into a non-amp source, but that said headphone would not be powered correctly and you wouldn't be getting the most outta it. As well using a hp ic that's on a sound card, if that ic is not giving enough power that needed as well, That will make the headphone not sound like it should.
There are many purposes. The amp is the most important piece of equipment when it comes to SQ, just after the speaker/headphone itself. After comes the quality and implementation of the dac chip and then all the other whistles and bells on the sound card, this include all kind of software DSP and the likes, which are implemented by the drivers. Idealy, you would like to bypass all that, and feed the stream directly to the dac itself, without any kind of software manipulation by the OS and by the soundcard drivers, in order to get de most of it. If you don't belive me, try setting foobar or musicbee with wasapi and see for yourself. The amp is resposible for most of the noise and distortion that goes into the headphone, so a better headphone amp would be a flatter, less noisy and with less distortion, besides with more power. So, building a very good amp can be expensive because they are the "analog" part of the equation, and so, the hard part of the equation most of the time. The HD650 need a bit of amplification, but if you get something realy power-hungry, the ST would start strugling to feed it and because of it, start distorting, maybe clipping and other kinds of bad things, so more power manytimes do translate on higher quality because you have more headroom to work with. The ST have enough power to make the HD650 sound loud enough, but that doesn't mean that they have the cleanest and more controled power you can get. Besides, one thing is the power you need to have a decent volume if you are feeding it with a high-volume source (think about pop/rock music with hoover's around 0 dbfs), and so most of the time you don't realy need a high gain, the other is to get a quiet classical piece that can suddenly get realy, realy loud (e.g. symphony surprise), the amp should have enough volume to get a quiet sound audible without needing to get too close to it's limit, so it can have headroom to deal with large volume fluctuations. This is one of the problems that makes amp designing not so easy as it might seem, and the more dificult to drive the headphone is, the harder the amp is pushed. The ST/STX are awesome cards by themselves, but they have a very good dac implementation, very clean RCA outputs and a so so amp implementation, but the overall package is unbeatable by the price............... if you can live with the quirks of the card. In order to beat the ST internal amp, you would have to go to something in the US$ 250-350 to start with, and that's just the amp, and suposing that you are still using the ST's RCA outputs, so you need to double the price of the card just to get a better amp. If it's worth it, only you can tell, but I belive it enough to be considering spending in a near future something like that. Edit: I hadn't seen GenClaymore answer when I started writing. It's just as he said, even if you can get the headphone loud enough, you may not extracting the most of it because of either distortion, noise or lack of current.
For someone with a mITX mobo, like me, an external DAC and AMP is what you can do to get better sound quality aside from different headphones or headgear. However, this gets retarded expensive and yea, the cheaper gear (under $50) is almost no different than onboard audio. The hard part about everything audio is that unless you can hear it in person, you kinda just buy on impulse based on reviews and suggestions. I personally wouldn't have a DAC/Amp setup that is more expensive than the headphone used, but that is how it's mostly priced. Put your money toward better headphones first. The recent Schiit Magni and Modi combo ($99 each) appears to be a good deal, has gotten good reviews, and I plan to pick up the combo soon. http://schiit.com/cart/index.php?main_page=product_info&cPath=0&products_id=14
There is another reason for an external amp. Digital audio in computers (and in portable players) use the original source volume level as 100% of volume while playing. If 100% of that level is too loud for you then you dial down say to 50% (in player UI). And to achieve that 50% of original level player subtracts (digitally) 50% of amplitude signal value from the original signal. And that can lead to loss of audio details. If you have external amp then you can set 100% of volume level in player UI and control comfort level via (analog) external amp controls.
Yea because if you do asio or wasapi without a amp, they disable the volume control for bit match playback, which cause you to go flying out your chair from the loud volume, only to get pulled back down by the headphones.
Yep, definitely gotta be careful with that without an external volume knob, that's a quick way to get some mighty serious hearing damage.
Nice responses, thanks for clearing it up. Do the same things apply to speakers? I wanted to pick up a pair of audioengine A5+ at the end of the month. But if I need to drop an additional $300 on an external AMP to make them sound good I'll have to look at other options : /
Funny, I was going to pick those up for my new place when I have the money. Although I think the optional subwoofer is pricey. Audioengine is a respectible brand with affordable gear. I think they would sound great out of any source.
Another reason is that there usually is a lot of electrical interference inside a pc case which can negatively impact the sound output. Using an external DAC and AMP makes sure there is nothing interfering with the signal which can quite easily be corrupted when it's analog. Which it always is when it is send from the AMP to the headphones/speaker.
I have a pair of Denon AH-D7100 headphones ($1200) and an external AMP/DAC from Headroom ($850). Without the external AMP my computer at work can barely power the headphones. The guys at Headroom designed the AMP/DAC to completely bypass the onboard sound. All I do is plug the AMP via USB into the MOBO rear panel and the RAW signal from my CD/DVD drive goes directly to the AMP where the digital signal is processed and sent to the phones. I know this hardware is high-end but it demonstrates what everyone here has been saying. I suggest a vist to Headroom's site...they have tons of information and very good tutorials on all this so you can make an informed decision.
http://www.jdslabs.com/item.php?fetchitem=O2Full Buy / build one of these. Good sound doesn't need to cost the earth The Modi / Magni both look interesting though - but I imagine the O2 would outperform the Magni. Unless you really do need 1W+ into your headphones. That said, the Magni is a nifty idea. And it's a bit cheaper I'd want a Class A output in a headphone amp though if I was going for a discrete one.
