[James63]

I have a quick question. I use Apple computers so I have an optical out built into my computer.

Is there any benefit for me to spend the extra $275 to get the USB version? To me it makes more sense to use the optical connection to separate the mechanical drive from my amplifier.

I will be using this mainly with a Mcintosh MA6300 integrated amplifier and B&W 703 speakers..... and of corse headphones.

 

[CSMR]

For not much more than $275 you can get a good soundcard and a respectable headphone amp so no.

 

[majid]

The only difference would be that the USB models have the latest electronics compared to the older non-USB model, but if you buy direct from Benchmark, it shouldn't make any difference.

My Mac is a dual 2GHz Powermac G5, and its optical out is limited to 44.1kHz 16-bit, so in theory I could get higher bit rates from the USB version. Most newer Macs support higher bit rates in their optical out. you can check the System Profiler or Audio MIDI Setup to be sure.

 

[James63]

Majid:

The highest bit-rate my mac puts out is 96.0kHz @ 24 bit.

I rip all files using Apple lossless format. I have no idea how the details works. It looks like the DAC-1 USB is limited 96 kHz 24 bit and the optical can take up to 192 kHz 24 bit. So technically the DAC-1 is better over optical out.

All in all it might be a moot point if the DAC-1 is limited to 96 kHz over USB and my computer is limited to 96 kHz over optical out.

What I don't understand is what is my limiting factor. Is it the computers output, the sample rate it was encoded at, or the DAC-1 conversion?

Also does it matter what wether the CD was ripped at 16 or 24 bit, or it that just part of the play back?

For what ever it is worth my current system sounds more natural to me with my computer set at 44.1 kHz 16 bit, using lossless files sent over optical out to my pre/pro. At 96.0 kHz 24 bit my speakers sound "tizzy" and unnatural? I am blaming poor audio conversion inside the mac?

Edit:

From benchmark's website for OS X:
"The system sample rate must be set to match the sample rate of the files being played". What would this sample rate be for lossless files?

Edit #2: It looks like I found my own answer. Apple lossles sample rate is 44.1, 48 kHz. Comparison of audio codecs - Wikipedia, the free encyclopedia

More input on the DAC-1 would still be very appreciated.

 

[majid]

I would guess the 96kHz limit on USB is due to USB itself, or the Benchmark implementation of USB. The poor quality at 96kHz would be due to sample rate conversion, since 96 is not an integer multiple of 44.1.