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Adaptive versus asynchronous DAC´s

N

nbaptista

pfm Member
Is asynchronous DAC´s definitely a winner or is adaptive another way to achieve the same results?Benchmark and Rega both use adaptive in the past with good results, I think!
 
In reality, the USB connection type doesn't matter so much. It's just that if audio is going to be re-clocked by the receiver, an asynchronous connection makes more sense. Otherwise, a buffer is needed and if timing is way too off, there is the risk of overrunning the buffer.

But what matters more is that data is appropriately re-clocked on the receiver. It's perfectly possible for a DAC that establishes an adaptative connection to deal with jitter better than a DAC that makes an asynchronous one.

Having said this, I wouldn't buy nowadays a DAC with a USB implementation that is not asynchronous, if only because it would reflect that it doesn't use the latest technology.
 
talkinghorse said:
Asynchronous USB is perhaps the more fashionable but this engineer's blog attempts to explain the reality.

http://nwavguy.blogspot.co.uk/2012/04/odac-released.html
Click to expand...

From the blog:

A NOTE FOR 24/88 FANS: Some have asked about 24/88 high resolution audio support (popular for SACD rips). While the ODAC doesn’t support 24/88, it does support the audibly identical 24/44. It’s trivial to re-sample 24/88 audio to 24/44 with no artifacts as it’s a simple divide-by-two operation (and one the operating system will perform for you automatically).


This is very wrong. I'm wondering if this is just a late night rant and hence something he'd correct if pointed out, an over simplification for the masses, or a display of ignorance about how to resample audio which would question his knowledge of digital audio processing.

To clarify, it's the divide by two i'm questioning, not the 24/88 vs 24/44 being indistinguishable (it is to me, but i'm happy for others to think otherwise).
 
russel said:
I have that DAC, or I used to, I gave it away, its too bass light, which I suspect is caused by layout, Fiio D3 sounds better and cost less.
Click to expand...

That's interesting. Being bass light isn't normally an issue with layout. As he measured it flat, this suggests some sort of build problem for your one. Duff DACs tend to sound grainy, or screechy to me, but they all have wonderful solid bass as that is totally trivial to get right for a DAC.
 
For various DACs in Stereophile (11kHz sine from analogue out) non-async USB is often the worst measuring digital interface and async USB is often the best measuring, though not always.
Cesare said:
Being bass light isn't normally an issue with layout. As he measured it flat, this suggests some sort of build problem for your one.
Click to expand...
Devices that measure flat can be perceived to have different tonality IME.
 
I'm looking to get a DAC and have been reading loads but am a little confused now about async vs adaptive USB and how it affects the features of the software players, perhaps someone can clarify a few things for me about the different connection methods.

My source will be 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 adaptive USB or 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 that were at the top of my list (for buying secondhand) 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 DAC in a similar price range (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.

Thanks :)
 
occamsrazor said:
And given that, could you suggest a DAC in a similar price range (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.

Thanks :)
Click to expand...

Audiolab M-DAC ?
 
tomek said:
Audiolab M-DAC ?
Click to expand...

Thanks. Yes as I mentioned that's at the top of my list. But I'd like to know if there are any other worthy options at that price level which fulfil the above needs. But more on-topic to this thread I'd like to confirm about the integer mode only on asynchronous USB thing.
 
AFAIK "integer mode" is just OS X language for "bit perfect", bypassing the OS mixers (like WASAPI on windows).
 
nbaptista said:
If so, you can use either an adaptive or asynchronous DAC.
Click to expand...


Apparently not. I don't know if it's a limitation of the protocol or it has to do with the USB driver already in OS X that most asynchronous DACs use. But in order to use integer mode, both the player and the DAC must support it, and it has to be through asynchronous communication.
 
Unless the USB port of the DAC requires a custom driver I think 'integer mode' is purely a function of OS X.

On the wire the transfer will almost inevitably be a form of 'integer mode', regardless of how your player supplies the samples to OS X. You should be able to find a USB exploring tool that will let you examine what the actual settings are in use.

Paul
 
Nbatista,

Do yourself a favour and take your adaptive usb rega DAC to compare it with a good Asynchronous USB dac.

In theory (and IMO in practice) the asynchronous one should sound clearly better.
 
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