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UNDERSTANDING FILE UPSAMPLING AND CONVERSION
PCM TO DSD CONVERSION
Through use of our TruBit™ Upsampling technology as described below, it is now possible to convert
PCM files to DSD. For those that prefer DSD this is an extremely powerful feature. Imagine taking
any source or sample rate (excluding MQA files) from network, internet, Bluetooth, AirPlay, or SPDIF
and converting to DSD64, 128 or 256. Whether you're in the PCM or DSD camp, AiOS
accommodates both! Not only can you convert any PCM sample rate up to 768 kHz in the PCM
domain, TruBit™ Upsampling also allows you to convert that 16, 24 bit PCM to a 1-bit direct stream
digital signal with sample rates of 2.8224 MHz (64 or standard rate), 5.6448 MHz (128 or Double
rate), 11.2 MHz (256 or Quad rate). You can even up-convert a native DSD64 file to a higher level
of DSD128 or DSD256. By using superior no compromise AKM DACs and our exclusive 128-bit DSP
engine, any native DSD or PCM to DSD converted signal is processed as true DSD. In other words,
AiOS does NOT down-convert a DSD signal to PCM within the DAC chips. This is actually somewhat
rare as many so called DSD players actually down-convert the DSD signal to PCM inside the DAC
chip(s) without you knowing it.
PCM AND DSD UPSAMPLING
TruBit™ Upsampling is a powerful upsampling technology used to upsample lower sample rates
(excluding MQA files) to higher sample rate and increases the bit depth to 32 bits for PCM and 1 Bit
for DSD in the digital domain via a dedicated 128 bit DSP engine prior to analog conversion. This
can be very useful in achieving a more enjoyable listening experience. Once a native input signal is
changed to a selected higher sample rate, the bit depth will also automatically increase to 32 bits for
PCM or change to 1 bit for DSD conversion. However, like all powerful tools, this too should be used
prudently. We do not take a blanket "higher is better" approach to upsampling. It is important to
experiment with different rates depending on your source or source material. Many times a native
rate might be preferred whereas some recordings or file formats might benefit from a higher
sampling rate, and so on.
The available selectable sample rates depend on the input signal's original sample rate. For
example, above 192 kHz the available PCM rate(s) will only be in multiples of either 44.1 kHz or 48
kHz as follows:
Input signal rates of 44.1 or multiples of:
44.1 ---> 48 ---> 88.2 ---> 96--> 176.4 ---> 192 ---> 352.8---> 705.6 ---> DSD64 ---> DSD128 -
--> DSD256.
Input signal rates of 48 or multiples of:
48 ---> 88.2 ---> 96--> 176.4 ---> 192 ---> 384--->768 ---> DSD64 ---> DSD128 ---> DSD256.
If "BYPASS" appears momentarily next to Upsample Rate it means AiOS will pass the input signal
rate out in its native rate without any upsampling.
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