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DAC Amp for AKG K702

Discussion in 'Portable Headphone Amps' started by jaredtkatz, May 31, 2010.
  1. jaredtkatz
    I have a pair of AKG K702s that I've used unamped with my Macbook for a while. Despite claims that these "need" large amounts of amping, these are relatively low impedance headphones and anyone here who knows a thing or two about electronics might be able to realize how misguided some of these claims are.  Whatever the case may be, I'm looking for a decent DAC/Amp combo around $150 or less. I was waiting for the E7 for a while, and if it receives good reviews, perhaps I'll go for it. Otherwise, what other options do I have? I used to have a D2 Boa but not while I had the K702s; would that be a good option?
    Any input would be great!
  2. catchedge
    I'm also curious with this exact setup.  I'm looking at using a Ibasso D10 but I'm not entirely sure yet.
    So for now, Bump in hopes of an answer
  3. rbf1138
    Just started down a similar path as you guys. I just bought and am still waiting for my K702s, but in the meantime, I just bought the Nuforce uDAC, which was $100. I'm figuring out amps now. The Little Dot MK II and III are in consideration, but are above your price ranges. I'd like to hear what others suggest for this setup, although your target of $150 total seems low for anything decent, based on what I've been finding browsing around Headfi. 
  4. Happy Camper
    The 64 ohm is deceiving. You need a good 1/2 watt to drive them decent. If the amp's dampening strength don't carry enough current to have total control over that driver, it will sound weak and hollow. Like the difference between a portable vs a dedicated high voltage power supply amp. 
  5. hockeyb213 Contributor
    I would recommend something like a d10 > rx unit since the d10 has a amazing dac and the rx can drive full size cans better then any portable amp I have heard to date. As for a single unit I don't know of any unit that I am particularly happy with but maybe a pico or a d10
  6. rbf1138


    Care to elaborate on what this "rx" is, lol? 
  7. hockeyb213 Contributor
    http://www.32ohmaudio.com/store/index.php?main_page=product_info&cPath=63_68_86&products_id=480 it is a amp made by alo audio which is able to pump a ton of current for hard to drive cans and sounds brilliant imo.
  8. rbf1138


    Thanks, but that sounds well out of the range of the stuff we're looking for in this thread
  9. jaredtkatz
    Ok, since I only use the k702s at home, maybe I can get a desktop DAC/Amp like the Head-direct / HifiMan EF2?  Also, it's good to see other people in the same boat!
  10. rbf1138
    Just as an update: I'm awaiting my uDAC from Amazon ($100), and I went out and bought a Cute Beyond amp today ($180). Should be a pretty good pairing! 
  11. Jack C
    Sensitivity on the K702 is rated as 105dB/V, the V I assume is RMS. This means that the K702 provides 105dB of output at about 16mW of power. 160mW would be 115dB. That is quite loud.
    For comparison, a reference level home theater, which is very loud, averages 85dB and peaks at 105dB, with the subwoofer channel running 10 dB hotter at 115dB peak.
    Most people do not listen at reference levels and usually settle on about -20dB for casual and -10dB for "spirited".  Any louder than that for sustained periods will result in hearing damage.
  12. dofindale
    Interesting Jack. Would you please explain to me in detail how that formula works again pls. Been a while since I took physics.
  13. Jack C
    No problem... here's how it works:
    105dB/V per the AKG K702 specs indicate to me that the headphones generate 105dB of output when fed a 1Vrms signal.  The formula for average power is Vrms squared divided by the impedance: Pave = (Vrms)^2/R
    1^2/62 = 0.016, so 16mW, to get 105dB of output.
    Every 10x increase in power brings 10dB of output, so a 160mW input would generate 115dB of output from the K702.  The K702's maximum rated input power is 200mW, which means 116dB is about the maximum it is designed to output. 
    ookic likes this.
  14. dofindale
    awesome, im gonna have to sticky this.  Only thing i can do to rate headphones being in Hawaii is these boards, and specs. unfortunately we dont have much selection here.  This will help me make pairing decisions in the future. thank you.
    just thought of something, how did you get 1 for the vrms?
  15. Jack C
    Actually, you are not much worse off than the rest of the country. There are very few precious physical shops left where you can sample/try the higher end gear.  All of my headphones, I've pretty much had to rely on a fair bit of faith before ordering. :)
    The 1 for Vrms is due to the unit that AKG uses, which is 105dB/V, when expressed this way, it means literally "105dB per 1Vrms".

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