• Mac Pro Quad Boot Reference Music Server

    The reference music server that goes to eleven! Last month I published my reference music server article that continues to draw a very large audience. To date the article has received 122 comments and thousands upon thousands of views. I also published an article on my initial Mac Pro configuration with OS X and Windows Vista. Since then I decided to take it up a notch. That's right, all the way to eleven. My Mac Pro now runs OS X Leopard, Windows XP Professional 32-bit, Windows Vista Ultimate 64-bit, and openSUSE 11 (Linux). Whether or not this is the best of both four worlds remains to be seen. However there is no better way to test applications and sound quality across operating systems than using the identical hardware.
     

     

     

    Mac OS X Quad Boot Music Server
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    The Reference Music Server That Goes To 11

    All of you are familiar with booting and rebooting your computer. That's a given. When Windows Vista was introduced more and more people started dual booting their computer with Vista and XP. This allows the user to select Windows XP or Windows Vista when the computer boots. If a user has applications that only work on XP but still wants to use Vista the cheapest solution is dual booting.


    When Apple switched to the Intel platform it included an application called Boot Camp with OS X. This application allows OS X users to dual boot into OS X and another Windows operating system like XP or Vista. The setup is very simple through the Boot Camp graphical user interface (GUI). Once OS X and Windows are installed on a Mac the user can select to run either operating system by holding down the Option key upon booting their Mac. Without holding down the Option key the Mac boots into OS X unless Windows is selected as the default startup disk.


    Here at Computer Audiophile there is no end to the different configurations needed when reviewing a product or conducting tests before publishing an article. In addition the only way to conduct apples-to-apples software tests is to use the exact same hardware. This left me with one option, quadruple booting a Mac Pro. Configuring a Mac Pro to quadruple boot is no easy task. If you're like me and you don't read instructions it is business as usual trying to quadruple boot. That's because there really aren't any instructions available. Bits and pieces of information are all over the Internet. I spent countless hours going back and forth between sites trying to put this puzzle together. Now that I've done it I could easily do it again fairly fast. Or maybe not. As usual I didn't write anything down during the laborious process of trial and error. Note: More error than anything else. With my quadruple booting Mac Pro I am presented the screen above (see photo) with the OS choices upon boot-up. If nothing is selected OS X will boot automatically. This is nice for me as OS X is my first choice for an operating system and I can reboot the music server remotely without user intervention.

    With four operating systems installed I should be able to test almost every media playback application available. Plus the Berkeley Audio Alpha DAC enables me to test for bit perfect output. As I mentioned previously I have a host of applications lined up for testing. Right now I am listening to Jewel's album Spirit using MediaMonkey on Windows Vista Ultimate 64-bit. And, I can say definitively I am getting bit perfect output (see photo below). There is no end to the Internet chatter about Windows Vista and the lack of audio quality. At least we have visual proof it can be bit perfect. This leads me to a topic that is currently being discussed in the forums. The sound signature of different applications. I can guarantee with 100% certainty that iTunes on OS X and MediaMonkey on Windows Vista Ultimate 64-bit are bit perfect and DO NOT sound the same. Since my Mac Pro is running both operating systems and applications there are no hardware differences to obfuscate the results. Even the AIFF files were the same as I accessed the music off my Thecus 5200B Pro NAS unit. Sure both operating systems are different, but bit perfect is bit perfect. Or isn't it? To some these results make perfect sense. To others they make no sense. To me, I honestly have no idea. I certainly don't have all the answers but I will continue researching this topic. One thing I do know is that I enjoy listening to music on both systems. Isn't that what this is all about? Much more to come on this and related topics.



     

    Mac OS X Quad Boot Music Server
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    Comments 36 Comments
    1. pichonCalavera's Avatar
      pichonCalavera -
      I'll be very interested in knowing the results with openSUSE 11. What software are you going to use on openSUSE for playback? , one of the most popular in the Linux world is Amarok.<br />
    1. Poo's Avatar
      Poo -
      Hey Chris, can you please explain (or point me in the right direction if you have previously) how the Berkeley Audio Alpha DAC enables you to test for bit perfect output? I'm sure it's quite simple, but I can't imagine how it does this. Is it a matter of comparing the original signal to what is output? If so, how can one be sure the original is bitperfect?<br />
      <br />
      Would love some more info... nice quad boot BTW, although I'm glad it's not my machine
    1. cs's Avatar
      cs -
      Hi Chris,<br />
      <br />
      I'd be interested in how it verifies 'bit perfect' too.<br />
      <br />
      In the past, I have done this in a rather convoluted way, by importing the two files to be compared into some signal processing software (Agilent SystemVue), then performing a mathematical subtraction. Only if the result is zero over the entire file length, is the comparison 'bit perfect'.<br />
      <br />
      Interesting that the files sound different. This possibly points to a short term sample rate anomaly. Maybe one of the OS's doesn't perfectly re-time the samples it gets from memory ?<br />
      <br />
      Chris.
    1. BEEMB's Avatar
      BEEMB -
      Chris,<br />
      <br />
      Looks great, all those operating systems on the same hardware.<br />
      <br />
      You tease us by saying they sound different, and are both bit perfect ... but which sounded the better ?
    1. The Computer Audiophile's Avatar
      The Computer Audiophile -
      Hi pichonCalavera - I'm going to try as many as I can that appear like viable solutions. I will likely start with Amarok.
    1. The Computer Audiophile's Avatar
      The Computer Audiophile -
      Hey poo and Chris - The Berkeley Audio Design Alpha DAC verifies bit perfection when playing an HDCD encoded track and illuminating the HDCD indicator when all the bits are passing through perfectly. Don't quote me on this, but I believe the HDCD flag is in the 16th bit. Any bit variation and this flag will not be passed to the DAC. Thus the HDCD indicator will not illuminate. All of the common things like using a digital software volume control and using the wrong output plug-in in MediaMonkey will not allow the HDCD indicator to illuminate.<br />
      <br />
      I think comparing two files with software like Agilent SystenVue is a good thing to guarantee your files are identical. But, it doesn't help determine if the playback application like MediaMonkey or iTunes is passing the track bit perfect to your DAC.<br />
      <br />
      The sound differences between bit perfect applications are definitely interesting. Like I said earlier, I don't have the answers, but I am continuing the research. Hopefully some other readers can test a few applications and share their opinions.
    1. The Computer Audiophile's Avatar
      The Computer Audiophile -
      Hey BEEMB - I'm not ready to answer that question yet. I know which one i like better right now, but it would be a disservice to pick a winner without many more extensive listening sessions. I know that's kind of a lame answer, but it's an honest answer.
    1. cs's Avatar
      cs -
      Hi Chris,<br />
      <br />
      OK, thanks.<br />
      <br />
      In John Atkinson's review of the AE, he indirectly proves that iTunes is bit-perfect :-<br />
      <br />
      http://stereophile.com/digitalprocessors/505apple/<br />
      "Some audiophiles have dissed the AirPort Express on the grounds that its digital output is not bit-accurate. However, I found that this was not the case, that the data appearing on the AE's digital output were identical in the original file. To check this, I compared a WAV file with a duplicate that I had captured on my PC from the AirPort Express's S/PDIF output. I used iTunes on my PowerBook playing a version of the file encoded with Apple Lossless Compression to feed data to the AE. The files were bit-for-bit identical, proving that the AirPort Express is transparent to the music data (as is ALC, for that matter). "<br />
      <br />
      So, if the bits are right, the only other thing to get wrong is the sample timing. Presumably, OS X sounded best ? It is de facto in recording studios after all.<br />
      <br />
      Chris.
    1. The Computer Audiophile's Avatar
      The Computer Audiophile -
      Hi Chris - I think we should clarify a little bit more what he proved. In my opinion he proved the combination of iTunes and the Airport Express are bit perfect. I am pretty sure that iTunes by itself on a PC is not bit perfect.<br />
      <br />
      Good link though!<br />
      <br />
      I am withholding my opinion, for now, about which systems sounds better :-)
    1. cs's Avatar
      cs -
      Hi Chris,<br />
      <br />
      Yes I think you are right.<br />
      <br />
      John Atkinson's test used iTunes on his Powerbook (OS X) to stream to the AE, whereas the captured file on his PC was pre-stored from the SPDIF capture.<br />
      <br />
      All my tests on file comparison were done using iTunes on my iMac. I only use Windoze when I absolutely have to, and run it as a VM using VMWare Fusion.<br />
      <br />
      Chris.
    1. The Computer Audiophile's Avatar
      The Computer Audiophile -
      Hey Chris - Have you done any listening through VMWare Fusion. I know that sounds painful, but I am just curious. I spent about 5 minutes listening with my XP / Parallels combination and called it a day. It's far too convoluted with the virtual layer between the OS and the hardware.<br />
      <br />
      I can't see anyone actually doing this, but you never know :-)
    1. cs's Avatar
      cs -
      Hi Chris,<br />
      <br />
      No I've not tried that.<br />
      <br />
      I only really use XP for running scientific / engineering apps which have no OS X equivalent :- Mathcad, SystemVue, and Microwave Office, which is a professional electronic circuit simulation package. Using these apps, I find I get ~ 80% native Windows performance.<br />
      <br />
      Chris.
    1. jimim's Avatar
      jimim -
      Hey Chris I'm assuming you are still using the AES connection on the PCI card to the DAC? What other DAC;s out there use AES do you know just for ref?<br />
      <br />
      jimi<br />
      <br />
      PS you are nuts you know! 4 operating systems? you should be the other guy on the mac pc commercials, wonder what they would say to you? LOL
    1. Roseval's Avatar
      Roseval -
      I think the claim of being able to detect bit perfect input is a bit to much.<br />
      Inputs like S/PDIF or AES/EBU are unidirectional, no way to establish if they are bit perfect on receiving.<br />
      It is a claim not made by Berkely and not by the inventors of the HDCD, Pacific Microtronics (http://www.vt52.com/ftp/semi/pmd100.pdf)<br />
      The claim that you are playing a HDCD when the HDCD led is on, it a valid one.<br />
      If its on, it probably means that at least the LSB is not altered and maybe this applies to the other bits as well. http://en.wikipedia.org/wiki/High_Definition_Compatible_Digital<br />
      <br />
      Playing digital audio invokes many steps:<br />
      - the Codec to interpreted the contents of the audio file<br />
      - DSP by the player software<br />
      - the driver to route the audio to the sound card<br />
      - the sound card to convert the audio stream to S/PIDF (you are probably using the optical out so S/PDIF over Toslink)<br />
      <br />
      Using different OS, the codec, the player software and the driver are different.<br />
      Letís assume that in case of simple formats like AIFF or WAV (uncompressed straight PCM audio) the software donít make a difference.<br />
      Letís assume everything is bit perfect regardless of the OS.<br />
      What is left is the jitter.<br />
      S/PDIF sends the signal as a bit stream (so digital therefore robust) but the sample rate is derived from the rate at which the bits are pouring in. This is depended on the sender, the clock of the Toslink. A clock is a analogue device. Thatís the hybrid character of S/PDIF, digital signal but analogue timing and therefore analogue imperfection.<br />
      <br />
      It might be that the Toslink produces more jitter as the system load increases (more EMI/RFI and/or dirt on the power). If this is audible, it means that the DAC is sensitive to input jitter to.<br />
      It might also be that the claim of bit perfect is false. In absence of any specification of your testing procedure it is almost impossible to establish what might be a cause.<br />
    1. Nels Ferre's Avatar
      Nels Ferre -
      This may be wrong, but I thought iTunes dropped the ability to pass an HDCD signal after Ver. 6.4?<br />
      <br />
      Four OS on one machine? That's flat out sick! And here I was proud that I can dual boot on my MacBook.....<br />
      <br />
      <br />
    1. Poo's Avatar
      Poo -
      Thanks for the extra info on bitperfect detection Chris, although I'm not sure I understand any better how the Berkeley unit does this in such a foolproof manner. I guess there is also an assumption here that the rip or file itself is bitperfect, though I'm sure few of us ever check; in fact in some situations (buying music on line for example) we generally can't check the accuracy of the file. It is the 'real life' situations like these (though this is a small example) that make me sit back a little and wonder if these 'reference' systems pull more wool over our eyes than anything else at times... "The little green light is on so it is OBVIOUSLY bitperfect!"
    1. The Computer Audiophile's Avatar
      The Computer Audiophile -
      Hi Nels - I'm in contact with the people from Pacific Microsonics, or what was PM, regularly and I can say iTunes still passes HDCD.
    1. The Computer Audiophile's Avatar
      The Computer Audiophile -
      Hey Jimi - Yeah, I'm still using my Lynx AES16e PCIexpress card and the HD26 to XLR AES cable. There are quite a few DACs around that support AES. I would say more support AES than USB. The Stello DA100 Signature that I recently reviewed has an AES input. It will only handle up to 24/96 though.<br />
      <br />
      Ok, so I'm a bit nuts with the quad booting music server. I love the comment :-)
    1. jimim's Avatar
      jimim -
      sorry should have added upto 192?<br />
      <br />
      jimi
    1. The Computer Audiophile's Avatar
      The Computer Audiophile -
      Hi roseval - Welcome to Computer Audiophile. I also checked out your site and like the information you have there. <br />
      <br />
      Thanks for the detailed post. I value your opinion but disagree with it for the most part. I talk to the co-founders of Pacific Microsonics regularly and I am very confident with my statement that illuminating the HDCD indicator on the Alpha DAC equates to bit perfect output. If the HDCD indicator illuminates on the Alpha DAC, the data is uncorrupted. Theoretically, it is possible to alter HDCD data using specialized software while not touching the LSB, but all of the typical mechanisms that might alter data in a computer environment such as level shifting, dither, SRCís, etc. will definitely affect the LSB. And, if the LSB is altered the HDCD code is lost. So, as a practical tool, presence of the HDCD light indicates no alteration of the data file. <br />
      <br />
      In my system I am using a Lynx AES16e digital I/O card that outputs via AES. The Lynx card has around 20 picoseconds of jitter. I also use the clock on the Lynx card. I'm not a big fan of the Toslink output in general. I playback uncompressed AIFF files using iTunes. The Audio Midi sample rate is always set to match the sample rate of the music I am playing. <br />
      <br />
      <i>"...In absence of any specification of your testing procedure..."</i><br />
      <br />
      I hope it is clearly evident that I am not running a scientific laboratory test. <br />
      <br />
      <br />
      Anyway, thanks again for your post and I hope to see you share your thorough knowledge of this topic elsewhere on Computer Audiophile.