Dmm53,
To better analyze your results, could you tell me what output method you're using in Media Center? As a rule of thumb, the DSPs in Media center should only be used if you've got a less-than-ideal situation, such as a home theater. A lot of the options are there to accommodate SW cut-offs, or legacy receivers that aren't capable of decoding higher resolutions. You're W4S DAC is capable of playing native 24/192 files, so you shouldn't need any of the DSPs. Also ensure that your Windows sound device settings are correct. Make sure Media Center can take exclusive control of the output device, etc.
To more directly address the question, you theoretically shouldn't be hearing a difference when using up-sampling or oversampling. For example: If you're playing a Redbook CD rip (16/44,1) and up-sampling it to 24/192, you're only padding the output with additional 0's. No information is added, but the sample size is just much larger. Depending on the output method, you may be experiencing some other interactions with the Windows kmixer that are doing more harm than good.
To better analyze your results, could you tell me what output method you're using in Media Center? As a rule of thumb, the DSPs in Media center should only be used if you've got a less-than-ideal situation, such as a home theater. A lot of the options are there to accommodate SW cut-offs, or legacy receivers that aren't capable of decoding higher resolutions. You're W4S DAC is capable of playing native 24/192 files, so you shouldn't need any of the DSPs. Also ensure that your Windows sound device settings are correct. Make sure Media Center can take exclusive control of the output device, etc.
To more directly address the question, you theoretically shouldn't be hearing a difference when using up-sampling or oversampling. For example: If you're playing a Redbook CD rip (16/44,1) and up-sampling it to 24/192, you're only padding the output with additional 0's. No information is added, but the sample size is just much larger. Depending on the output method, you may be experiencing some other interactions with the Windows kmixer that are doing more harm than good.