The timing in most USB connections today is controlled by the converter or the DAC, not by the PC. So, there should be no timing issues specific to the PC. All it has to do it keep the buffer full and deliver the data when asked. I guess it is possible that the USB on the PC does not handle the interrupt request from the converter/DAC correctly, but I think that is a remote possibility. In any case, that should be independent of the CPU and disk usage, unless the USB implementation is really bad.
People are concerned about electric noise on the USB ground and on the signal lines, as well as RF noise from the PC that can effect the converter or DAC. That is why the devices I mentioned earlier are available. More and more equipment has galvanic isolation on the data lines, usually in the form of small transformers. Expensive cables can be used to try to eliminate RF problems on the cable and connectors.
Using a separate +5V power supply certainly makes sense if the USB device is powered by the +5V on the USB cable. Certainly, a $500 linear power supply will be much cleaner and more stable that the signal on a USB. However, that has nothing to do with file formats, HD usage, CPU usage etc.
As to bit identify files in the same format sounding different, that makes absolutely no sense to me. In the Absolute Sound article I mentioned, the authors said the sound go worse the more times files were converted, even if they ended up bit identical. I will say, they did get a lot of push back on that topic. However, others do report similar experiences. But, hey, if people believe they hear differences, that is up to them.
If people think they hear differences from all these things, who as I to say? For me, these effects are interesting to think about, but I don't hear most of the differences that these people report.
I did not mean to get this thread off topic, just wanted to summarize some of the issues that people discuss.
People are concerned about electric noise on the USB ground and on the signal lines, as well as RF noise from the PC that can effect the converter or DAC. That is why the devices I mentioned earlier are available. More and more equipment has galvanic isolation on the data lines, usually in the form of small transformers. Expensive cables can be used to try to eliminate RF problems on the cable and connectors.
Using a separate +5V power supply certainly makes sense if the USB device is powered by the +5V on the USB cable. Certainly, a $500 linear power supply will be much cleaner and more stable that the signal on a USB. However, that has nothing to do with file formats, HD usage, CPU usage etc.
As to bit identify files in the same format sounding different, that makes absolutely no sense to me. In the Absolute Sound article I mentioned, the authors said the sound go worse the more times files were converted, even if they ended up bit identical. I will say, they did get a lot of push back on that topic. However, others do report similar experiences. But, hey, if people believe they hear differences, that is up to them.
If people think they hear differences from all these things, who as I to say? For me, these effects are interesting to think about, but I don't hear most of the differences that these people report.
I did not mean to get this thread off topic, just wanted to summarize some of the issues that people discuss.