Which USB implementation, Benchmark built-in or ?

The Off-Ramp uses a low-jitter Superclock4. The Benchmark DAC-1 USB uses a simple inexpensive crystal. The Benchmark DAC-1 USB sounds very nice, and the reclocking that upsamples to 24/192 does help eliminate some of the jitter, but there are quite a few areas of improvement still possible. The stock unit is a great value though.

Considering the well-known deficiences of the S/PDIF interface, why bother with a USB to S/PDIF converter when you can get a cleaner solution with the Benchmark USB DAC1 that eliminates S/PDIF altogether?

Elias Gwinn, a Benchmark engineer, recently stated on an audio forum that "the USB signal is first converted to I2S, maintaining its original sample-rate. I2S is a fundamental form of digital audio. When an AES/EBU or S/PDIF signal is streamed to the DAC1 via XLR/coax/optical, it is also first converted to I2S at its original sample-rate. The front panel switch chooses which of these I2S signals are sent to the next stage: the sample-rate converter (SRC) chip. This converts the sample-rate of the I2S signal to 110 kHz, regardless of the original sample rate."

Search this and other audio forums and you'll find that S/PDIF has significant flaws, including poor error correction. High end audio has been saddled the S/PDIF interface, but now Benchmark and other manufacturers have developed USB DACs that eliminate S/PDIF from the signal path.

The bottom line is that if you are considering a Benchmark USB DAC1 or the non-USB DAC1 which requires a USB to S/PDIF interface, you will be better off with the former.

Lbenoit,

I understand what you are saying, and I tend to agree.
However, an external USB to S/PDIF converter offers flexibility in choosing a DAC of your preference.
I have not heard Benchmark DAC-1, based on some reviews it sounds cold and analytical, for this reason I am reluctant to buy it.
So my dilemma is, will this additional and seemingly unnecessary conversion to S/PDIF in an external converter destroy all the benefits you may gain by selecting a DAC you prefer that does not have USB interface?
It would be an easy choice if I could hear and compare all the devices, but it is not possible.
For example, do I go with USB to S/PDIF converter driving my MF X-DAC, or LavryBlack DA-10 which I am considering as replacement for MF, or do I go Benchmark DAC-1 with no USB to S/PDIF converter in the chain, assuming Benchmark will outperform any other DAC fed from external USB to S/PDIF converter, simply because of this additional conversion step.
What a pain this hobby is.