24-bit via MacMini USB?

[AlmaataKZ]

Here is a quote from Benchmark HDR;s manual:

---------------- The problem with native USB audio devices has been their inability to stream audio at sample-rates over 48 kHz and at wordlengths over 16-bits. Benchmark's AdvancedUSB Audio™ technology extends bit-transparent native USB audio to resolutions up to and including 96 kHz, 24-bits. ------------

On the other hand, I hear that USB is (inherently?) limited to 16 bits.

So, how do these 2 statements stack together? does a DAC like Benchmark HDR suddently make USB out (e.g. on MacMIni) to do 24 bits? and, if yes, how? What are they on about?

 

[Anonymous]

Some thoughts: Universal Serial Bus is an interface, a way of connecting devices to a computer. Any manufacturer may invent their own USB device, by making the hardware and writing a USB driver that 'talks' to this hardware, based on the basic implementation of USB. This could be any device. There are also alternative drivers for USB Audio devices (Ploytec) with lower latency than the standard WinXP driver (useful for recording studio applications, not needed for simple playback of audio).

On the other hand, there are also standard USB applications, i.e. specific extensions to the USB specs, such as USB Audio, or USB Memory devices. This means that a manufacturer can build a USB audio device according to the specs, without having to worry about the driver, it will work out of the box with the standard USB audio driver provided with the OS. The standard USB audio spec's is indeed limited to 48k/16b max.

So my first guess was that they built there own driver to allow the higher sample rates. But apparently this is not true, and they state that no additional drivers are required. Either they found a workaround to let the USB Audio driver work outside the official specs, or they use an alternative USB driver provided by the OS, and designed the hardware to accommodate that driver.

 

[VoodooDoctor]

I can confirm that it doesn't need another driver to do 24-bit. It just... works.

 

[AlmaataKZ]

I think Wavelenght is another manufacturer who does 24bit USB, but they do have custom drivers.

No custom drivers with Benchmark. so, how is that possible? natively 16 bit limit, but if you connect this box (and without custom drivers) - 24! How?