A question here for Peter @wklie
Hi Peter.
I have read reports that the Wolfson WM8471 DAC’s in my A1 perform technically ‘better’ when processing DSD/DFF files, over PCM.
Is this true, and in the A1 implementation of the WM8471, and putting purely sonic considerations aside. is there a technical advantage to setting the A1, or indeed Roon to upsample PCM to DSD by default, rather than native processing in PCM?
Many thanks.
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Regardless of any theory of what should sound best, ultimately you need to try both native PCM and PCM upsampled to DSD, and see which sounds better to you. There are people who really love the sound of DSD (original or upsampled), and there are people who really love the sound of non-upsampled PCM. You may even recall the manufacturer of your other streamer had a paper explaining that DSD is bad for music in 2013, but then added support for it in 2017 (to my surprise).
Between Roon DSD upsampling and Lumin internal DSD, the former has the advantage of giving you multiple parameters to tune it.
Try both non-upsampled PCM and Roon upsampling to DSD, and tell me which you like.
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Cheers for this Peter.
I’ve had a listen over the last few weeks, and I’m tending to prefer upsampling PCM to DSD, rather than listening to native PCM on the A1. I just wondered if there was a ‘technical’ reason behind it, that’s all.
I think as listeners we ‘like’ to establish sound ‘reasons’ for our preferences, hence my query. But you’re absolutely right - it’s the listening that matters.
And yes, as I think you’ve seen in a previous question, I leave the Nucleus to do the conversion, which leaves the A1 to receive a DSD stream.
As to that ‘other’ manufacturer you mention, yes, I thought it was quite interesting they featured DSD capability in their recent line-up. You never know? In another ten-years time they might get around to offering MQA capability!? 
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There is indeed a technical reason behind it. I’ll steal jussi_laako’s explanation for the concept (although the text refers to HQPlayer, the concept generally applies to software-based DSD upsampling before feeding a DAC):
All modern DAC chips are delta-sigma designs, meaning that PCM input needs to be converted to high speed bit-stream. As said earlier, DAC chips typically convert PCM input first to 352.8 or 384 kHz PCM using a digital filter of varying quality and then use stupid sample-copying (sample-and-hold/zero-order-hold) to take the rate up to typical 5.6/6.1 MHz speed for the delta-sigma modulator to produce the bit-stream for the actual D/A conversion process.
What HQPlayer is doing is not adding any additional processing to the chain, but replacing the processing performed by DAC chip with better implementation done in software. So HQPlayer performs high quality digital filters taking the sampling frequency straight to 5.6/6.1 MHz or even higher 11.3/12.2 or 22.6/24.6 MHz, without any quality compromising sample-and-hold stages and then converts it to bit-stream for the actual D/A conversion using high quality dithered delta-sigma modulator.
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