Does PSAudio use the I2s clock supplied by the output device, or the DAC?
Does the quality/stability of the clock impact the musical presentation? …pretty sure this is a yes…
If yes, how does PS Audio insure clock stability?
I have been reading a Aurender thread where clock stability is claimed to be of very high quality, but they don’t support I2s in any format.
It depends on the DAC, the Perfectwave DirectStream doesn’t use the I2S clock for timing. It samples the inputs at a high rate, then pattern matches the clock and data, decodes the data and puts it in a buffer. The quality of the I2S clock doesn’t matter at all. The DS’s internal clock is a high quality low phase noise crystal oscillator with high quality power regulation and filtered control signals. There is no worry there.
Thank you
How does this differ from Directstream’s USB input?
I recognize that USB is bidirectional, but couldn’t you use the same sampling method as with the I2s?
As far as the FPGA is concerned USB is an I2S input. So, once again, clocking isn’t an issue. The practical difference between various inputs is how well the cables are grounded/whether they cause ground loops in the rest of the system. With USB there’s also the noise that’s inherent with having power in the USB cable right next to the data over a long distance. That electrical noise from the source is audible in many setups.
That clarifies things.
Thank you.
Will the Mk2 have USB input? Innuos users like me (and PS Audio) have very low noise power as the USB output has a dedicated internal linear power supply. What is long distance? USB is not suited to long distance at the best of times. I use a 0.6m long USB cable.
The Mk II does have USB, it’s a ComTrue chip instead of the XMOS chips in previous units. The Mk II has a separate isolated power supplies for the USB and the I2S inputs. Those along with galvanic isolation for the communication between them and the rest of the digital card should lower effects of noise noticeably.
Long distance in this case is a meter or so. USB is limited to five meters between devices and/or hubs. The noise comes from the transitions in the data lines adding noise to the power and ground lines.