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Music encoding formats vs DAC hardware options

  1. dfoss
    I just joined the site. I'm looking to purchase some external audio gear - probably two separate boxes: a DAC and a headphone amp. I've looked at Schiit stuff and Topping so far. Hopefully this is not too much of a newby question - but here goes.

    My question has to do with the compatibility of the DAC I might buy with different music file encoding formats such as MP3, FLAC, WAVE, DSD, AAC, etc. I'll use whatever DAC I end up getting with Windows 10 and some version of playback software.

    Given all of the file encoding formats out there, does the DAC I buy need to explicitly state that it accepts a particular format I want to use (like MP3, DSD, etc), and if it doesn't explicitly say so, - should I assume that it won't play that file format? In the back of my mind, I also wonder if the playback software I use might convert certain file formats to common ones (like WAVE) first then send the converted stream to the DAC. This would of course make sense, so that we aren't always having to buy new DAC hardware every time there is a new audio compression format.

    I know that the Schiit stuff doesn't support DSD, and looking at a Topping D10 DAC, I don't see anywhere that it supports MP3 - they only list PCM and DSD.

    Any help or experience shared is appreciated.

    Grimbles likes this.
  2. Pentagonal
    Hi Dennis! Welcome to Head-Fi! A valid question, so here's my take on explaining it.

    Music encoding formats such as AAC and MP3 store PCM music bits (which make up CDs and most recorded music) in a compressed way to save space but discard some musical data to save space. WAVE and AIFF are file formats that contain the full original data that would be on the CD or master track. FLAC (Free Lossless Audio Codec) and ALAC (Apple Lossless Audio Codec) are the same data but are compressed without losing any musical data.

    The Digital Audio Player (DAP) such as your computer, phone, or iPod will always convert those MP3 / AAC / FLAC / ALAC / WAV / AIFF files into an uncompressed bit-stream that is sent to the DAC. If your player can play the file and talks to your DAC, your DAC will usually play the file too.

    One exception is if the file is DSD and your DAC can't play DSD. DSD is the same idea but the bit-stream that is sent to the DAC is fundamentally different. Some DACs can accept a DSD bitstream and others can't. Some computer audio players are able to convert DSD files into PCM files in real time to get around this.

    For what it's worth, I use the TIDAL streaming service which streams music in FLAC which my computer uncompresses on the fly and then sends my DAC a bit-stream that is identical to the CD it came from.

    I hope that is a good intro! Please let me know if you have any further questions :)

    Last edited: Mar 14, 2019
    Monsterzero and Grimbles like this.
  3. Grimbles
    Nicely said!
  4. Grimbles
    Pentagonal likes this.
  5. tomb
    Tidal is no different than any other music player running on the computer that can play FLAC (or mqa). It's still sending it through PCM to your sound card or DAC, where it is converted to an analog music output. There is nothing wrong with that. In fact, Tidal quality is one of the best available, period.

    There are really only two types of digitally encoding music: PCM or DSD. The incompatibility comes from the fact that PCM is present in probably 99% of all equipment that can record and decode analog music.

    PCM, or Pulse Code Modulation, was the original digital form that was developed and used to create the first Compact Disc, follow-on digital tape, and digitally encoded video. PCM was set originally with the Compact Disc at a 44.1kHz sampling rate. Twice the amount of the 20kHz audio spectrum, plus some extra for overhead, was thought to be the theoretical amount necessary to fully capture 20kHz audio and below. Lately, the limitations of the analog recording equipment and analog filters were recognized as limiting the theoretical capture of the 20-20kHz audio band, so higher sampling-rate versions of PCM have developed (48kHz, 96kHz, 192kHz, etc.)

    DSD is a completely different digitally encoding system for analog audio than PCM. It was developed specifically for the SACD disc format. Thus, electronics used at the base level for encoding or decoding PCM are incompatible. There are drivers/plug-ins, etc. that will work through some music players such as Foobar2000, but that music player is still converting the DSD encoding to PCM before sending through a PC's sound card or a DAC. As noted above, there are very few integrated chips in existence that can directly convert DSD. More of them are appearing all the time, but it's still well below the amount of PCM electronics that have existed since the 80's.

    All the other acronyms cited are different computer data file formats, some with compression algorithms, either lossless (FLAC) or lossy (mp3). All of those are handled in software or through the computer's operating system (OS). PCM or DSD is at the base level in the DAC integrated circuit chip.
    Last edited: Mar 14, 2019
    Pentagonal likes this.
  6. Grimbles
    Reasonably predictable but nevertheless tedious. Ultimately (within appreciably limitied bounds) sufficient. Never factually incorrect. Never personally engaged.

    Well done son. You engaged boring.
  7. tomb
    Ever more accomplished than fragmented clausal comment ...
    ProtegeManiac and Grimbles like this.
  8. dfoss
    Thanks to each of you for the commentary responding to my questions about the compressed digital music format world.

    It seems from the answers I read that the traditional DAC chip designed into the higher-end products is designed to accept a standard Pulse Code Modulated signal, and the better ones out there are able to accept the data stream at rates much faster than the original 44.1 kHz speeds (like 48, 96, 192, and 384 kHz), and with traditional 16 bits, or 24 and even 32 bits per sample. That is the standard feature in the DAC, and then there are a few sexier chips that can also take raw DSD formatted inputs as well. For all other music coding types - apparently the music playback application software is responsible for pulling apart the native format and converting it to a suitable PCM format prior to sending the stream to the DAC hardware.

    Assuming I have this correct, the selection process for equipment comes down to whether I want to add native DSD input capability in addition to the various PCM rates... AND how capable he DAC is at providing high quality analog output characteristics - low THD, timing dither, gain flatness, linear phase, etc.

    Anything I'm missing ? If not then I think the picture is fairly clear. I have to admit the whole picture of spending $100s of dollars for a dedicated single input DAC and headphone amp seems pretty nutty, considering that you can buy a perfectly good quality home theater receiver with built in headphone output port for the same price (or less) and get so much more functionality. Is there something about that solution that is highly sub-par?

  9. Grimbles
    Sense of humour engaged, smile forms. Good show :)
  10. Pentagonal
    I used to use a near top-of-the-line Marantz SR8500 receiver (bought used for a great price!) to drive a set of Magnepan SMGA speakers. Great and incredibly pure sound! Though the sound was astonishingly good, the headphone out wasn't very good, buzzed, and was scratchy.

    I am now starting to approach the sound with my earphone setup that I had in my old living room system with a Chord Mojo DAC+Amp combo with Etymotic ER4s earphones connected through Toslink Optical from... an optical converter connected to my iPhone! The Mojo is special in that it is an affordable DAC that has an FPGA in it, basically a small custom computer, that digitally removes jitter and applies Chord's custom "WTA (Watts Transient Alignment)" filter that sounds very good to my ears. It is the first time a headphone kit that I have owned has made me feel goosebumps like my Marantz+Magnepan setup gave me.

    Perhaps you could create a decent headphone setup out of a home-theater receiver but it wouldn't be the best tool for the job. It has lots of additional amplifiers and circuits built in which may detract from sound quality. Additionally, you shouldn't use the Digital Signal Processing or THX that it offers in order to preserve sound quality. And once you remove all of the $extra$ that aren't relevant to headphone use, the headphone amplifying circuitry in the home theater receiver may be a $5 circuit compared to what would be perhaps a $50 circuit in the dedicated headphone amp.

    I want have a DAC+Amp that sounds pure, free of digital noise and distortions, and gives me great music. I chose the Chord Mojo because it's battery powered (clean power isolated from AC or USB noise), portable, can be used with optical isolation via Toslink, has an FPGA to remove most of the influence of jitter from that Toslink, has Chord's WTA filter, and it puts a smile on my face! :)

    Out of curiosity, can you tell us more about how/where you plan to listen?

    Grimbles likes this.
  11. dfoss
    I love Magnapans. There are no other speakers I've ever seen that produce such a uniform and wide listening angle and the highs are really smooth. My home system is McIntosh and B&W gear. Nothing new or fancy, in fact all very old.

    I haven't ever seen the Chord Mojo, but I've heard of it and now looked it up on the web. Interesting looking box with three colorful buttons.

    My interest in the external / portable DAC gear centers around work mostly - i am tired of listening to hiss and crap coming out of my PC and the playing of 160-320 kbps MP3 music (I have alot of music ripped in that range + the original CDs), in spite of using a NAD amplifier and a very small 2.1 speaker setup with sounds suprisingly good if only the source audio were better. I may also want to listen with phones from time to time and I'm trying to decide if an all in one DAC / phones amp would suit my needs or a separates solutions so that I can always leave the DAC on the PC and use the phones amp where I need it.

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