[CharlesC]

It seems to me that getting digital music data delivered from computer to D A C should be pretty straight forward.  I believe a USB2 connection has more than enough bandwidth to get the data where it needs to go reliably. So what's the point of having special drivers for certain USB DACs? Does the stream need to be smoothed out? Is it to support HiDef sources?
 
The reason I'm asking is that I really like my Surface 2 (ARM) and it's full sized USB port, but I find my selection of DACs is rather limited, at least for the time being, due to special drivers being unavailable for this not-yet very popular platform.
 
Thanks!

 

[FraGGleR]

  It seems to me that getting digital music data delivered from computer to D A C should be pretty straight forward.  I believe a USB2 connection has more than enough bandwidth to get the data where it needs to go reliably. So what's the point of having special drivers for certain USB DACs? Does the stream need to be smoothed out? Is it to support HiDef sources?
 
The reason I'm asking is that I really like my Surface 2 (ARM) and it's full sized USB port, but I find my selection of DACs is rather limited, at least for the time being, due to special drivers being unavailable for this not-yet very popular platform.
 
Thanks

Windows can't natively process over 24/96 audio streams via USB and needs special drivers to work with devices that go over 24/96.  Windows RT is a specialty quasi mobile version of Windows that works on a different architecture than normal computers, so unless Microsoft anticipated lots of people using USB DACs with their Surface 2 (and why would they?) it would be up to the DAC manufacturers to make custom drivers.  Have you tried any USB 1.0 DACs?  The USB 1.0 protocols have been around much longer so you might have some luck there.

 

[CharlesC]

Thank you, Fraggler, for the reply.  The default window's driver seems to work well with my Nuforce uDac-2.  The driver defaults to 16/48 and when I have changed to 24/96 my system becomes more hiccup prone. So I'm leaving it at 16/48 for now.  I asked because I've been looking at the Schiit lineup and find that only their lower end D A C uses the windows default drivers, all the others requiring special drivers.  The manufacturers seem to not make guarantees even with respect to the RT windows drivers.  Hard to tell if this is due to lack of experience with them or bad experiences, I hope it's the former.  Thanks again for answering my question.
BTW, Surface 2 marketing does claim that it supports USB audio.

 

[kurt bermuda]

  I believe a USB2 connection has more than enough bandwidth to get the data where it needs to go reliably. So what's the point of having special drivers for certain USB DACs?

 
What follows is an opinion, for reasoning's sake, not a fact...
 
The only reason I can think of is device features or compatibility with DAW software or mixing software (desirable for signal routing and mixing if a user wants to go in that direction). It is a case of hardware software intigration. No other reason really.
 
 
edited out BS

 

[kurt bermuda]

  Windows can't natively process over 24/96 audio streams via USB and needs special drivers to work with devices that go over 24/96.

 
That's interesting. Thanks for posting that.

 

[blueangel2323]

Windows resamples and applies some degree of DSP to your audio, even if you turn all the effects off. Some special USB drivers allow the computer to send a bit-perfect audio stream to the DAC.

 

[Roseval]

 I do know this is a fact, DACs don't need drivers if all they are doing is converting a signal from 0s and 1s to an electrical signal on a physical board.

The answer is simple.
All devices need a driver. If you don’t believe, open (talking Windows) the control panel > Device manger and ask for properties of any device.
Each time you will see a specific device driver.
http://en.wikipedia.org/wiki/Device_driver
Small wonder, a HD works a bit different than a printer or a mouse ore a keyboard or a DAC.
 
DACs are no exception to this rule.
The USB standard has two protocols for audio UAC1 and UAC2.
The first allows for sample rates up to 24/96 (full speed) UAC2 allows for >>> 24/96 (high speed)
UAC2 is available in OSX and Linux. MS don’t support UAC2 and nobody knows if they are even thinking about it.
Hence you need a third party driver for DACs > 96 kHz on Win.
 
Another case is manufactures of USB DACs that don’t use UAC1 or UAC2.
They write their own driver (in general using bulk mode).
As drivers are OS specific, these DACs only work on supported OS.
A bit more detail can be found in my website:
http://thewelltemperedcomputer.com/KB/USB.html

 

[kurt bermuda]

   
All devices need a driver.

 
That's what I thought. Until I saw this:
 
http://schiit.com/products/modi
 
 
"USB Powered, No Drivers
Modi plugs into virtually any computer—Windows, Mac, and some of the most popular Linux distros, as well as iPhones and iPads—and requires no drivers"

 

[StudioSound]

  That's what I thought. Until I saw this: http://schiit.com/products/modi
 
"USB Powered, No Drivers
Modi plugs into virtually any computer—Windows, Mac, and some of the most popular Linux distros, as well as iPhones and iPads—and requires no drivers"

 
All devices need a driver, but UAC1 devices will work with the system's built in driver rather than requiring you to install one.
UAC2 devices require you to install a driver on Windows because it does not have one built in. Macs do not, because they have native UAC2 support.
I don't think devices like iPhones and iPads will work with UAC2 devices either.
 
A number of DACs will actually let you switch them between UAC1 and UAC2 mode depending on whether you need support beyond 24/96, or compatibility.

 

[kurt bermuda]

Thanks for all the info. Stuff I need to know.

 

[CharlesC]

Thanks for all the replies.  Very interesting stuff.  I had assumed that all a computer had to do was unpack an MP3 file then send the resulting bits out to the D A C.  Clearly there is more to it than that. Expecting bad weather this weekend so maybe I'll dig in to The Well Tempered Computer.

 

[TrollDragon]

The Burson Conductor SL I had here supported 24/192 right out of the box with no drivers needed on Windows 7. There was a new CMedia USB module installed in it as opposed to the older Tenor chip.

 

[StudioSound]

The Burson Conductor SL I had here supported 24/192 right out of the box with no drivers needed on Windows 7. There was a new CMedia USB module installed in it as opposed to the older Tenor chip.

You must be mistaken, Windows does not have built in drivers for USB Audio Class 2.
Perhaps it's using drivers from a previous DAC which happens to use the same USB chips?

 

[TrollDragon]

Probably not...
 
The Burson shows up as "Speakers" in the Playback Devices list, since my FiiO E17 only does 26/96 in USB I was really curious as to what would appear for the Conductor SL.


These were the choices I was given... I had renamed the device from "Speakers" to "Burson Conductor SL" in the General Tab
Burson does provide a CMedia driver that will bypass all the audio effects that can be enabled in the Enhancements panel which I did not bother with.
 
From there I went straight into foobar2K Output: WASAPI (event) Burson Conductor SL after it was renamed from "Speakers", the FiiO E17 shows up as WASAPI (event) SPDIF Interface (FiiO USB DAC-E17).
 
The Burson has moved onto the next listener in the program so I can run any tests or give you any more screen shot. I should have looked into it deeper to see what it was in fact using but I was more interested in hearing the Amazing LCD 3's

.

 

[StudioSound]

  The Burson shows up as "Speakers" in the Playback Devices list

That definitely sounds like it's using a driver that was installed with another device then. They also mention that you need to install a driver in the manual.
I'm not saying it's impossible, but it's probably not acting as a standard UAC2 device if that's the case. I think the former is a more likely scenario though.