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Asynchronous USB vs optical SPDIF, integer mode, recommended DACs


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I'm looking to get a DAC and have been reading loads but am a little confused, perhaps someone can clarify a few things for me about the different connection methods.

My source is a Mac Mini running Audirvana (currently using the mini's internal analogue output, soon to be with DAC instead) and I understand Audirvana's "integer mode" is the way to go, as it bypasses the Mac OS X audio system.

However yesterday I read that integer mode is only possible with asynchronous USB mode DACs, not optical SPDIF, which was the connection method i had planned to use.

On the other hand, I also read that USB-SPDIF converters like the Audiophilio support integer mode.

A couple of the DACs at the top of my list were the Audiolab M-DAC and Rega DAC (old version not the newer DAC-R). But if the Rega uses adaptive USB then I guess that would mean I can't use integer mode.

 

Could someone kindly confirm what is exactly the situation with all this?

 

And given that, could you suggest a suitable sub-$1000 DAC (or DAC + converter combination) that:

 

a) Supports integer mode

b) Ideally has both balanced and unbalanced outputs

c) Supports 24/192 on whatever the preferred input is

d) Has volume control (preferably with remote but not essential) enabling it to be used directly-connected to a power amp.

 

Thank you....

Mac Mini > RME ADI-2 DAC > Hypex Ncore monoblocks > ATC SCM-11 speakers & C1 subwoofer

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I understand Audirvana's "integer mode" is the way to go, as it bypasses the Mac OS X audio system.

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Side comment: these days (since Mavericks and also in Yosemite), MacOS actually has reintroduced the integer mode into the OS, so you don't need the Audirvana integer mode solution for this any more, and other players e.g. JRiver also do integer mode. It still is to my ears the best sounding playback mode, and I'm generally a big fan of Audirvana. That said, you're correct integer wont' work via optical.

 

On your suggested choice of DAC; you'll see in my signature that I have a very similar setup to the one you're considering (BelCanto m-link plus Exposure DAC), and while I like the sound of what i hear very much (and the analog side of the digital equipment matters more than many think), DAC technology these days is progressing very fast, and the two older options (Audiolab and Rega) wouldn't be top of my list. One of the key reasons for my Exposure dac was the integration with my Exposure amp (same look & shared remote), but you've got so many new options these days. I don't know how important native DSD is to you, but I'd clearly like to have it (in spite of the small handful of DSD files I actually have)

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Side comment: these days (since Mavericks and also in Yosemite), MacOS actually has reintroduced the integer mode into the OS, so you don't need the Audirvana integer mode solution for this any more, and other players e.g. JRiver also do integer mode.

 

Can you elaborate on this? How exactly is integer mode in the OS itself? I'm curious......

 

Thanks for your suggestions, much appreciated. Since I wrote that I found a good deal on an Audiolab M-DAC, and while I note your comments about it being an older option, I think I'll go with it. PS - I don't need DSD.

Mac Mini > RME ADI-2 DAC > Hypex Ncore monoblocks > ATC SCM-11 speakers & C1 subwoofer

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Can you elaborate on this? How exactly is integer mode in the OS itself? I'm curious......

 

Thanks for your suggestions, much appreciated. Since I wrote that I found a good deal on an Audiolab M-DAC, and while I note your comments about it being an older option, I think I'll go with it. PS - I don't need DSD.

 

Integer Mode seems to bypass most of the low level OS HAL layers like mixing and send the audio stream toward the lowest possible hardware layer I do not know if it is so better than not using INT Mode, but theoretically it is indeed better. INT Mode is available only via USB and up fro Maverick natuvely. In prior OSs it was a hack in A+ called Direct Mode, but I have info from Damien that even in Maverick you need to keep Direct Mode On, then Integer Mode with Mode 1 and HOG as well. No need for limit 24-bit data stream this is for bridge devices, but uncommon.

--

Krzysztof Maj

http://mkrzych.wordpress.com/

"Music is the highest form of art. It is also the most noble. It is human emotion, captured, crystallised, encased… and then passed on to others." - By Ken Ishiwata

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Can you elaborate on this? How exactly is integer mode in the OS itself? I'm curious......

 

Thanks for your suggestions, much appreciated. Since I wrote that I found a good deal on an Audiolab M-DAC, and while I note your comments about it being an older option, I think I'll go with it. PS - I don't need DSD.

 

Here's some more reading (a bit older) from Damien, the developer of Audirvana, on integer mode:

 

http://www.amr-audio.co.uk/large_image/MAC%20OSX%20audio%20players%20&%20Integer%20Mode.pdf

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Honestly, with a thousand dollars to spend, I'd suggest that you shouldn't worry yourself about Integer Mode compatibility. Many other factors will be much more significant in determining how you enjoy the sound of a DAC.

 

Don't do optical at that price point. You want something which the computer sees as USB. Either buy a DAC which has a reputation for being awesome with its built-in USB, or buy as good a USB-to-SPDIF (coax) converter as you can manage along with a DAC known for sounding awesome with a good SPDIF "transport".

 

The vast majority of DACs in the above categories will support 24/192 anyway. So you just have to look at whether they have the other features you care about (eg balanced and single-ended outputs) and try to audition a couple to "get your ears in", after which what you read other people write about the sound of different DACs will convey a bit more meaning.

 

Try reading some of John Darko's DAC reviews at digitalaudioreview.net - he likes to emphasise the under-$1000 options.

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In my experience, integer mode has a large positive impact on the sound quality of a DAC. I primarily use Audirvana and wouldn't buy a DAC that didn't support integer/direct mode.

 

That's fine and all... but it's a powerful thing to have some understanding of what "integer mode" actually is and how and why it can affect the sound quality.

 

Are you aware that all SPDIF PCM data transmission uses integers, 100% of the time? Or that 24-bit integers such as we use for PCM audio samples are able to be conveyed with absolutely perfect accuracy inside a 32-bit floating point data format and then retrieved again?

 

The point of "integer mode" is merely to reduce the number of conversions between integer and floating point formats. Not because these conversions damage the data (they don't) but because the act of converting involves an electrical action in a circuit somewhere which can influence the behaviour of other parts of the system by tiny amounts.

 

So for "integer mode" to be beneficial, you have to have a system whose performance is being audibly degraded by these tiny machinations. Most of the time, and especially in the sub-$1000 bracket, there are plenty of other factors which make a bigger contribution to the overall performance than this.

 

The right choice of USB interface can make integer mode irrelevant. The Audiophilleo 2 is a great example: it supports integer mode but it sounds consistently excellent whether you send it integers or floats. It does a great job of isolating the DAC from the foibles of USB. Partner something like that (especially a 2nd-hand one if you can find it) with an inexpensive but well-designed SPDIF-only DAC and you're off and running with quality computer audio.

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That's fine and all... but it's a powerful thing to have some understanding of what "integer mode" actually is and how and why it can affect the sound quality.

 

Are you aware that all SPDIF PCM data transmission uses integers, 100% of the time? Or that 24-bit integers such as we use for PCM audio samples are able to be conveyed with absolutely perfect accuracy inside a 32-bit floating point data format and then retrieved again?

 

The point of "integer mode" is merely to reduce the number of conversions between integer and floating point formats. Not because these conversions damage the data (they don't) but because the act of converting involves an electrical action in a circuit somewhere which can influence the behaviour of other parts of the system by tiny amounts.

 

So for "integer mode" to be beneficial, you have to have a system whose performance is being audibly degraded by these tiny machinations. Most of the time, and especially in the sub-$1000 bracket, there are plenty of other factors which make a bigger contribution to the overall performance than this.

 

The right choice of USB interface can make integer mode irrelevant. The Audiophilleo 2 is a great example: it supports integer mode but it sounds consistently excellent whether you send it integers or floats. It does a great job of isolating the DAC from the foibles of USB. Partner something like that (especially a 2nd-hand one if you can find it) with an inexpensive but well-designed SPDIF-only DAC and you're off and running with quality computer audio.

 

Lets use bit perfect instead of ineger to describe what we are trying to achieve. Integer mode guarantees that the OS mixer doesn't impact gain in such a way as to change the bits. The conversion to and from floating point in this scenario can damage the bits if gain or EQ changes are inadvertently applied.

 

So bit perfect mode is always relevant and yes you can get better sound by using a good USB bridge with SPDIF DAC, especially like the one you mentioned which as you also state supports integer mode.

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Bit perfect can be important, yes, but it's completely independent of integer mode. You can use Audirvana's software features such as upsampling or volume control to create an audio stream which is NOT bit perfect but which IS passing data from the application to the USB interface in integer mode.

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Bit perfect can be important, yes, but it's completely independent of integer mode. You can use Audirvana's software features such as upsampling or volume control to create an audio stream which is NOT bit perfect but which IS passing data from the application to the USB interface in integer mode.

Interesting, I thought that A+ IS bit perfect instead what you are gonna do? Except changing voluma/gain when in software.

--

Krzysztof Maj

http://mkrzych.wordpress.com/

"Music is the highest form of art. It is also the most noble. It is human emotion, captured, crystallised, encased… and then passed on to others." - By Ken Ishiwata

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Interesting, I thought that A+ IS bit perfect instead what you are gonna do? Except changing voluma/gain when in software.

 

"Bit Perfect" just means you didn't change anything between reading the audio file and sending its data on to the DAC. If you change the sample rate, or the volume level (in software), then you've... changed something. And that's not bit perfect.

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