Using a Topping D30 and not sure which input I should use. USB supports up to 32bit 384khz and Optical supports up to 24bit 193khz. I looked it up and optical has less signal noise compare to usb I don’t know too much about the bit rate and frequencies.
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TBH, they should be about the same, since you most likely don’t have any files over 24bit, but it’s really up to you. I just use usb because it works, but really there won’t be a quality difference that you could reasonably perceive. Just use what is more convenient to you.
Well if you go based off of what audiophiles say they can perceive all frequencies. Even though the human ear can’t go passed a certain frequency. But either or whatever works best for you.
You would be more concerned about electrical noise, latency, and jitter in this case if you wanted to compare USB to optical. You should be bypassing windows sound using asio or wasapi for best sound quality, and it would change the bit depth and sample rate on the dac to what you are playing, instead of upscaling it to what you would set in windows audio.
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what is ASIO and WASAPI and how do you use that to bypass Windows management of the sound?
If you use music software like foobar (or whatever else there’s a lot out there), for your music, you can use Windows Audio Session API (wasapi) or Audio Stream Input Output (asio) to bypass windows Direct Sound (ds) and bypass the volume mixer.
Windows direct sound will upscale all your audio to what you set in your device settings for that sound device in your sound settings. Wasapi or asio will allow for the sound to go directly to the device, and the device will be able to change its bit depth and sample rate to match exactly what file is being played, and will bypass windows sound. This will allow for bit perfect playback.
Weather you use asio or wasapi is up to you and there are honestly negligible differences between the two. some devices end up working better with asio and some devices end up working better with wasapi, it just depends on the device (some devices also may not support asio). although something to take into account is that both asio and wasapi take more processing power to maintain a low latency data stream. But you can always adjust your latency to prevent errors.
Both standards also prevent any other sounds from Windows or any other programs from playing when in use. Only the one specific software can use that device at a time, so you should use standard windows audio if you want to play a game (and hear audio) and listen to music at the same time. The standards take exclusive access to the sound device, so no other software or windows can access it when asio or wasapi is in use. If you want to configure this, check to see if your sound device can support either asio or wasapi, and see if your music playing software can support those standards as well. You may have to add a plug-in to the software or install a different sound driver for your device. Most manufactures already have asio and wasapi implemented into their drivers, so I would check if your player has support, and go from there.
There will most likely will not be a huge sound quality difference from direct sound to the asio or wasapi, but I do find that you are able to achieve a higher quality output with these standards, but can only notice this when critically listening. For most average listening without making a compromise direct sound is fine
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thanks for the explanation…however that’s a wall of text. you might want to break it up into more digestible pieces.
also, you mention processing power. is this on the part of the DAC or the source?
lastly, can you give some examples of current hardware that doesn’t do well or like WASAPI or ASIO?
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Sorry, that’s just how I think lol
If you set your latency too low, your computer might not be able to keep up with the audio and have buffer underruns. This will cause random pauses and clicks/pops because the computers processor and i/o cannot handle the lower latency audio.
It really does not matter regarding listening to music for pleasure, as is it’s more for talking about digital audio workstations using asio for live audio playback. You can avoid taking more processing power from your computer by reducing your latency, and it won’t really matter as long as you don’t have it set too high. Only care about this if you end up being effected by it.
An integrated motherboard sound chip probably will not support wasapi or asio (unless you use asio4all and force it to work), but most modern dacs will support wasapi and asio. I personally prefer wasapi because there are less things to configure and for the most part is set and forget, but is not as configurable as asio is.
Asio is necessary if you are using something like a DAW to create music, and need to use multiple inputs like multiple interfaces, and multiple outputs to different dacs. IMO just stick to wasapi, it works smooth with most USB devices and is relatively more stable then asio
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OP, sorry for the thread jack, but hopefully this information will be helpful for you.
M0N, I appreciate you taking the time to share this info!
PC’s are so powerful now that unless you’re using onboard audio, like you mentioned, processing power shouldn’t be a limitation anymore…6 / 8 / 12 and 16 cores are all the norm now for desktops, with 4 and 6 for notebooks!
Oh let me tell you, even a Threadripper 2990WX can’t keep up if you have your buffer size too low. It can be insanely picky once you get down in latency. You almost have to hand pick a build with parts that have been benchmarked for the lowest latency, and have specialized hardware and all that crap. Doing anything with advanced audio software can just immediately throw you in driver hell 
But for just listening to music even cheap laptops can get the job done just fine if you configure it correctly
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Went and installed wasapi and plugged both usb and optical to my pc. Guess I’ll have to take some time and test it for myself. Don’t think there are any big differences but I’m going to try and look for it anyway. I do have tracks on 32bit 48khz and lower.
It’s so subtle, but can help some people if their windows upsampling is particularly bad. Also what are the 32 bit tracks if you don’t mind sharing the name? It’s very rare for an artist to release any 32 bit things