Toslink to USB adaptor? And DAC opinions?

Discussion in 'Apple TV and Home Theater' started by mcdj, Mar 15, 2008.

  1. mcdj macrumors 604

    mcdj

    Joined:
    Jul 10, 2007
    Location:
    NYC
    #1
    I'm thinking of getting an external DAC, or maybe an integrated amp with a built in DAC, for the ATV. Some of them only have USB inputs (Bel Canto S300ui integrated amp for example). Is there such a thing as a toslink to USB cable adaptor? (am I even correct in calling the ATV's optical out "toslink"?)

    Alternately, do any of the USB hacks for the ATV enable audio out?

    Finally, can anyone using an external DAC comment on the difference in sound quality vs RCA out? I have to say, my 320kbps AAC files sound pretty darn good straight out of RCA into my stereo. I wonder just how much better they'd sound through a DAC.

    Thanks!
     
  2. VideoFreek macrumors 6502

    VideoFreek

    Joined:
    May 12, 2007
    Location:
    Philly
    #2
    A google search suggests that Toslink- (yes the :apple:TV digital output is Toslink) to-USB converters do exist, but I have no direct experience with them.

    I have to say, though, that I think you're making this way too complicated by going the USB route, and you will unnecessarily limit your options. The :apple:TV is built to be like a conventional piece of AV gear, and as such it is compatible with all audio receivers/ integrated amps/ pre-amps, which have optical and/or coax digital inputs. I think the boxes like the Bel Canto you mentioned are made to cater specifically to people who want to hook up their computer to an audio system, as computers normally lack things like HDMI and digital audio outputs.

    For my part, I run the Toslink out of my :apple:TV to my Rotel Home Theater receiver, thereby using the Rotel's DACs, and it sounds pretty good. I haven't done any direct comparisons between that and the analog outputs, however.
     
  3. jdavtz macrumors 6502a

    Joined:
    Aug 22, 2005
    Location:
    Kenya
    #3
    I have the Bel Canto s300iu. The difference between its DAC (via USB, obviously) and my iMac G5's DAC via its headphone-out socket is audible.

    It will depend on your amp though; the BC is a nice bit of kit - cheaper amps might not be able to resolve the differences.

    I've no experience with Toslink>USB devices.

    If you're already set up with ATV and have a decent amp already, then it might be better to buy a dedicated DAC rather than replacing your amp. If you're feeling rich, the Cyrus DAC-X or the Bel Canto DAC3 are options; I think the Benchmark DAC-1 is significantly cheaper.

    A DAC3 or DAC-X aren't very different in price from a s300iu, assuming you already have a capable amplifier.
     
  4. mcdj thread starter macrumors 604

    mcdj

    Joined:
    Jul 10, 2007
    Location:
    NYC
    #4
    Thanks for the info. I currently have an odd setup...an Arcam Solo CD (with no digital input), whose built-in amp I am bypassing for a Jeff Rowland 102.

    I use so few of the Arcam's features that is has basically become a glorified preamp, especially since I got the Apple TV and have all but stopped using the Arcam Rdock.

    The Rowland 102 amp is obviously the strong point of this rather mismatched system. My plan was to sell the Arcam and replace it with either a Rowland Capri preamp or replace both the Arcam and the 102 with a Rowland Concerto integrated (again no digital inputs on either).

    Then I caught wind of the S300iu, who some have said rivals the Rowland gear at half the price. But obviously the USB DAC does me little good with the ATV. So I guess there's yet another component/AC plug/IC in my future.

    The only reason I question a DAC at all is because so little of my music is currently in lossless. I have very few CDs to re-rip. I sold them all before I knew what I was doing conversion wise. The bulk of my collection is 192kbps mp3s. I can't help but wonder if even an S300iu can help such low-rez files.
     
  5. Avatar74 macrumors 65816

    Avatar74

    Joined:
    Feb 5, 2007
    #5
    192 Kbps MP3 is considerably inferior to 192 Kbps AAC, but to get around this you'll have to re-encode from the source. But I wouldn't even suggest a DAC in either case... it's not going to help improve the garbage that is 192 Kbps MP3, and it's not necessary for MPEG-4 AAC. It's not because AppleTV is an inferior product. It's because the formats used, and your own ears, are not going to be able to discern the difference.

    Unless a substantial portion of your content is all recorded, mixed and mastered to a 24-bit Linear PCM format, you're using content that won't significantly benefit from an outbard DAC.

    How did the idea even enter your mind? Did you read about DAC's in Stereophile magazine? Let me start by saying that audiophiles are the last people in the solar system you should listen to when it comes to audio equipment. They're all victims of confirmation bias. Pardon the bluntness but you have no idea how many times I've heard people ask this stuff and invariably I find out they've been brainwashed by audiophile morons who insist that their ears can tell the difference between Lossless and AAC when their brain can't tell that motion pictures are just a series of still frames changing 24 times a second!

    Take it from me... I engineer, mix, master and market my own content in 24-bit Linear PCM format. Even if you encoded everything not just in lossless but in 16-bit Linear PCM format, I'd tell you to save your money. There's no reason for an outboard DAC in this day and age.

    What exactly are you trying to achieve? Jitter mitigation? Jitter has not been a problem for digital systems since the mid-1980's. Almost all DAC's, even the cheapest ones today, resolve this problem with proper sample & hold buffering and internal reclocking of the signal. Alias filtering? Aliased frequencies are only a problem if the sample frequency is below two times the Nyquist limit (in this case, the upper end of the A-weighted range). What's more, most mastering processes include a 20kHz lowpass filter to ensure that any frequencies capable of generating aliases are filtered out of the master recording to begin with!

    Give yourself and your pocketbook a break... The AppleTV handles content up to 16-bit Linear PCM just fine. Just feed the optical straight to the receiver and let your receiver do the decoding. If the Sony PCM-F1 processor was sufficient for professionals in the early 80's, I'm sure whatever receiver you are using today has DA converters that are more than adequate to reconstruct the signal with imperceptible artifaction.
     
  6. mcdj thread starter macrumors 604

    mcdj

    Joined:
    Jul 10, 2007
    Location:
    NYC
    #6
    Normally I would side with a voice of reason like yours, but you're giving me conflicting advice. On the one hand you're telling me that I don't need a DAC, but on the other hand you say that I should just feed the optical to the receiver and let it do its thing. So which is it? Do I need digital conversion or not? Maybe you missed this part in my OP, but my amp has no optical in...RCA only. This is why I was asking about a DAC in the first place.

    I don't buy into much in the audiophile world. I have perfectly good speaker cables. They were $80. My interconnects were $20. But I can definitely hear a subtle difference between a lossless encoded track and the same track encoded at 320kbps AAC. So I was inquiring as to how much further a DAC might take that difference.
     
  7. Avatar74 macrumors 65816

    Avatar74

    Joined:
    Feb 5, 2007
    #7
    I didn't catch that part... No, you don't need an outboard DAC, just use the RCA outs on the AppleTV.

    No, you can't. Fundamentally, you shouldn't be able to hear the difference between 128 Kbps AAC and uncompressed 16-bit LPCM, nevermind Apple Lossless. If you really think you hear a difference, then it's your mind fooling you into believing there is one.

    It used to matter back in the day... such that a Burr-Brown DAC would make a significant difference. But that was more than 20 years ago and now the internal quartz oscillator clocks on desktop CPU's are just as reliable for sample synchronization as tens of thousands of dollars in hardware were 20 years ago. The AppleTV's DAC are more than adequate.
     
  8. tomate101 macrumors newbie

    Joined:
    Apr 29, 2011
    #8
    Avatar74: There are no RCA outs on the new AppleTV (black)

    MCDJ: I have exactly the same need. I want to connect my new AppleTV's Optical Audio Out to my Belcanto S300i's USB input. Have you found a way?

    In the upgrade options for the S300i on Belcanto's website I don't see any TOSLINK Input option.
     
  9. BeachChair macrumors 6502a

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    Apr 11, 2008
    Location:
    Copenhagen, Denmark
    #9
  10. ohio.emt macrumors 6502a

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    Jul 18, 2008
    Location:
    Ohio
    #10
    Considering the thread is from 2008 I think it's safe to say he has the old apple tv.
     

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