DoP versus Asio native – what are the differences/similarities?

ASIO native and DoP are two different ways to send DSD data through the USB audio subsystem. Both require hardware support (in the DAC) and software support (in the playback software).

The key difference is that ASIO has it’s own distinct protocol that packs 32 bit worth of DSD data into a PCM sample but support even on Windows is very limited and does mostly not exist on Apple& Linux.

Meanwhile, DoP is totally platform/device/driver agnostic but can only transmit 16 Bit worth of DSD data per 32 Bit PCM sample (the rest is used up by the protocol marker and other overheads).

So ASIO 88.2KHz native can transmit DSD64 while on DoP it needs 176.4KHz to transmit DSD data. Other than that fundamentally the two systems are very similar. Neither transcodes DSD into anything else, both use PCM Packets as “transport” and both re-assemble the original DSD datastream completely transparent and bit-perfect before it is sent to the DAC.

Specifically using DoP, DSD is sent as a 16-bit chunk per PCM sample. So DSD(64) requires 4 PCM samples to hold 64 DSD bits and thus it needs to be sent as 176.4kHz PCM. And thus DSD128 via DoP requires 352.8kHz PCM and DSD256 via DoP requires 705.6kHz PCM. Only via ASIO (native) is DSD sent at the DSD sample rate, though under the bonnet it is sent in effect as 32 Bit per PCM sample, so 705.6Khz allows 22.57M DSD sample rate (DSD512).

The key difference between ASIO native and DoP is the way DSD signals are identified and how many bits are available per sample. ASIO has a mechanism separate from the data to signal DSD and uses 32 bit per PCM sample. For DoP the DSD marker is embedded in the PCM data stream and only 24 Bits are used of which 8 Bits are used as the DSD marker.

Did this article solve your problem?

If you’re still having problems, why not contact the iFi Support Centre. We’re available Monday to Friday.