[dthoms]

I am looking for guidance on a laptop to DAC setup.  What hardware do I need to do 24/96 and up samples to a DAC?  My DAC (Bryston BDA-1) has fiber, coax, usb connections.  My main problem is finding the appropriate sound card to output to digital at the higher sample rates.

[BradJudy]

An M-Audio Transit is probably the simplest solution for getting 24/96 to a standard digital output from USB (http://www.m-audio.com/products/en_us/Transit.html).  Or, you could go whole-hog and use one of the Empirical audio options ($650-1000). 

There are a number of pro audio external devices that can output higher bitrate via USB or firewire, but I don't know if they buy you much over the Transit (other than things you don't care about like inputs, mic pre-amps, MIDI interfaces, etc). 

[djlackey5]

Forgive my ignorance on this subject, but if his Bryston DAC has a USB input, why can't he just plug in a USB cable from the laptop to the DAC?

[doctorcilantro]

I missed that you owned a Bryston, sorry.

You could go with Scott Nixon usb DAC or something like a Benchmark USB DAC. If you want optical out right out of the PC, I thought EMU (creative Pro) made one, but it's from Creative. Maybe M-Audio makes one. I'd rather have USB-DAC or connect to a PCMCIA card rather than have an external USB sound card (I've owned the 0202 in the past). Just more clutter.

http://www.soundblaster.com/products/product.asp?category=1&subcategory=205&product=10769

Oh and you're right about higher sample rate limitations. I think the EMU devices allow 96kHz over USB, at least mine did; not sure about that creative card. Best to go with a USB DAC then. One device, and one less cable too.

DC

[BradJudy]

Forgive my ignorance on this subject, but if his Bryston DAC has a USB input, why can't he just plug in a USB cable from the laptop to the DAC?

Because the USB input on the Bryston will only support up to 16-bit/48kHz resolutions and he specifically asked about 24/96. 

[doctorcilantro]

huh? He can disable upsampling and run 96kHz into the DAC unless I'm mistaken.

"UPSAMPLING
After the input stage, the signal goes to the SYNCHRONOUS upsampling circuit (sample rate converter). This circuit converts the digital signal from one sample rate and bit depth to another. In the BDA-1, the sample rate is increased from the input sample frequency (32K, 48K, or 96K upsamples to 192K and 44.1K or 88.2K upsamples to 176.4K). The 16 bits of depth (the CD standard) is increased to 24 bits. The added 8 bits are filled with placeholder information. This upsampling process provides a digital signal for later conversion to analog by the Crystal 4398 DAC chip. The upsampling process doesn’t add any new, but does put the data in a form which can better be translated by the DAC as described below. The advantage of this synchronous upsampling process is improved processing of the upsampled signal by the DAC chip, which was designed for higher sample rates and bit depths. There is also a noise shaping process implemented where “noise” within the audible spectrum is shifted up to frequencies above audible limits. An added advantage of this upsampling process is that a totally new clock signal is applied, which results in significant jitter reduction.

OPTIONAL UPSAMPLING FEATURE
A very unique feature of the Bryston BDA-1 External DAC is the ability to disengage the upsampling feature. You can compare an upsampled signal with a non-upsampled signal simply by engaging a switch on the front panel. This feature is functional when using sample rates of 44.1K, 88.2K, 48K, and 96K."

[BradJudy]

huh? He can disable upsampling and run 96kHz into the DAC unless I'm mistaken.

The USB receiver chip used in the Bryston only supports up to 16-bit/48kHz resolutions.  This is true of most USB DACs (Benchmark is one exception).  Any upsampling capabilities/defeating is moot.