DirectSDM checkbox Question

I only have PCM files and I’m upsampling to DSD 512 into Singxer>ultraRendu >Holospring.

I’m presuming that whether directSDM is checked or not should have no difference in my case.


Am I correct in this? My ears seem to tell me differently?


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With DirectSDM checked, PCM -> DSD conversion happens at fixed volume setting (about -2.5 dBFS in latest version). While unchecking it releases the volume control for adjustments.

Reason for locking the volume control for PCM -> DSD is that otherwise you could get nasty surprise if you turn down volume for PCM source and suddenly encounter a DSD track on playlist coming out at full volume because it goes through as is…

I’m thinking I prefer the sound with it unchecked so perhaps there may be some clipping occurring on some tracks at the locked volume that doesn’t happen at my -7dB normal level?

Or am I talking rubbish based on a paucity of knowledge of half understood posts?


I think your good John, I leave unchecked and my volume around -6 and experience no clipping, If I check it then I note that some clipping occurs, Volume knob would turn red and/or the limited counter in the time block on the HQP main screen would be above 0 as well.

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That is entirely possible. You can watch the “Limited” counter in HQPlayer main window to see if it is triggering the soft limiter with DirectSDM checked.

I certainly know material where even -3 dBFS is not enough to avoid overs because the source is so compressed and pushed to the max…

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