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iMac onboard DAC vs. external?

Discussion in 'Sound Science' started by mrheuristic, Dec 9, 2012.
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  1. d marc0

    I can't believe some people not getting it when you've repeated this statement so many times...
     
  2. bigshot
    Maybe they're hard of hearing.
     
    Eee Pee likes this.
  3. rigodeni
    I have a latest gen 2013 iMac, and a high end PC with a Create X-FI Titanium Fatal1ty Pro Sound Card ($120). For my testing I used my Sennheiser HD 600's direct connected, no amp. I used Winamp on the PC and iTunes on the Mac, with the same sources, mostly MP3 at 320 kbps. I never use EQ, so this was off in all tests.
     
    Both the Mac and X-FI have plenty to drive the 600's to dangerous levels, with no audible hum (SNR is equally good on both). I could not bear going beyond 70% volume on either one. But they did not sound the same to me at all. The Mac was noticeably more bass heavy, and lacked the sound stage and separation I heard on the X-FI. The mid's on the X-FI came through more, with a sparkle in the treble that the Mac was missing. In addition to this, although there was less bass quantity on the X-FI, I felt it was more composed and resulted in more definition. This became clear on songs with percussion instruments, you hear more detail with each stroke. Although I had to really listen analytically with each side by side to hear differences, they were clear.
     
    I would like to say the iMac's DAC is substantially better than my PC's on-board. However, most audiophiles agree that in general, a DAC affects audible differences more so than an amp. I found this to be true with my experience connecting my Fiio E11 and Bravo V2 amps through both the iMac and PC. The differences I hear with amplification are much more subtle than the differences I hear between the iMac and X-FI DACs. Therefore, regardless whether you have a PC or a Mac, I still suggest upgrading your DAC before getting amplification.
     
    I must disagree with bigshot completely that you cannot hear the difference between an iMac's DAC and a dedicated external one. I would venture to say bigshot probably doesn't own any high end DAC's himself. Just like with headphones, published specifications do not indicate very much about how a DAC will sound. There are several electrical design factors and materials that go into the execution of a quality DAC. There are numerous reviews of DAC's by Mac owners, like the Schiit Modi ($99). I have yet to read one that did not hear significant improvements. Note that some reviews have amps, but testing was done with the same amp on both the iMac and Modi. And this is just one example of a good sub $100 DAC.
     
     
  4. stv014
    Did you verify that:
    1. it is really the DAC that is making the difference (just because two amplifiers can both output loud sound, it does not mean that one cannot possibly clip or have much higher output impedance)
    2. you compare the devices at accurately matched (read: measured to be equal) levels
    3. all DSP (EQ, virtual surround, etc.) is disabled and you are comparing bit perfect streams
    4. sound cards are used with optimal mixer settings
    And, of course, since it is the Sound Science forum, it is reasonable to ask to test double blind as well, if possible.
     
    The large majority of casual DAC (and other) comparisons are sighted, not level matched, and the listener is expecting an improvement from the new gadget that has just been purchased. It is no wonder a difference is heard under such conditions.
     
  5. bigshot
    Do what stv014 suggests and the differences will likely disappear. Mac frequency response measures ruler flat. I'm not familiar with your PC soundcard, but I would hope it does too. They should sound the same if the frequencies they produce are the same.
     
  6. rigodeni
    Quote:
     
    My test environment, or reviews of external DAC’s by actual Mac owners, may not satisfy you. That is fine, because regardless of the environment, the findings will still be mine, not yours. So if you really want to be sure, because it sounds like you do, you should get your own external DAC and test it yourself under conditions that satisfy you. I did just that, and to me it was obvious. If you’re willing and able, I would love to hear your experience with your own test environment.
     
  7. stv014
    Quote:
     
    Why would I waste money on a device I do not need, for the sole purpose of proving a point that will then be ignored anyway ? With proper testing, chances are that I would not hear any difference compared to my existing equipment (that performs plenty well enough according to any tests I could do), which the audiophile crowd - who themselves usually avoid any kind of controlled listening tests - would just blame on "not having revealing enough gear" or defective hearing. It would not achieve anything useful.
     
    Quote:
     
    That is fine, but if you did not make it sure that your comparison is made in a fair way and with eliminating common problems that affect listening tests, then your experience is of purely anecdotal value, and should not be stated as a fact. You may think you heard a major difference, but it could very well have been imaginary, or the result of unmatched levels or incorrect setup/usage.
     
  8. bigshot
    I did a level matched A/B switchable comparison of a $900 SACD player, an iPod classic with an AIFF file through line out and a $40 Price Club Coby DVD player. It wasn't blind, but even so, once the levels had been matched, they all sounded exactly the same. I've done tests between my Mac Mini and my iPod and SACD player too. Same results.

    Level matching and direct A/B switching are the most important parts of a controlled test. Very slight differences in volume and delay between samples can totally throw off a comparison.

    My whole system is driven off a Mac Mini running AAC 256 VBR in iTunes. I guarantee you that it would blow your socks off. If you are evern LA, look me up.
     
  9. One and a half
    Quote:
    Why would you choose the two highest jitter output connectors? In comparison, the analog out is far better, best is to use USB or FW if you have the right DAC.
     
  10. Currawong Contributor
    Quote:
     
    Allow me to quote my own post from a while back showing that the noise from the output of my MacBook Pro is high. 
     
  11. rigodeni
    Because I like to work in OSX more, I will be upgrading to the JDS Labs ODAC next month. I will compare it with my X-FI and the iMac's on-board. I have no A/B switch or fancy measurement equipment, but I will try to get my wife to assist me with a blind test. I have heard the ODAC fairs very well in blind tests. I would like to know that I can't hear a difference because this would save me money. But I am confident I can.
     
  12. xnor
    Quote:
    Jitter problems with HDMI have been fixed years ago. S/PDIF is not the best for jitter, but what amounts are we talking about? Certainly not in the nanoseconds range. USB: not every receiver has USB inputs.
     
  13. bigshot
    Quote:
     
    All you really need is an extra preamp to balance the line levels with.
     
  14. stv014
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    Optical S/PDIF may have higher (but with a competent implementation still nowhere near audible under realistic music listening conditions) jitter, but it prevents ground loops, which are a common real problem with computer based audio systems.
     
  15. rigodeni
    Quote:
    Neither my E11 or my Bravo V2 have a pre-out :frowning2:
     
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