I think the problem with the USB sound card is different from the problem with the Earstudio. On the USB sound card, it takes in uncompressed PCM data and outputs a voltage. If there is any aliasing, it's due to only that process (PCM to voltage, possibly due to bad rounding and a lousy anti-aliasing filter). With the Earstudio, if AAC (and the USB DAC output, if that gets tested) show no problems, then it is not the PCM to voltage conversion that is to blame (testing the USB DAC mode of the Earstudio is probably the best way to confirm this, since it is taking in PCM data directly). The problem then lies with the Decoder, which takes in either compressed SBC and aptX and converts to PCM. There is likely to be more problems that result from the decompression process. WS is probably asleep; it's the middle of the night in Korea.