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Real-time vs. Off-line DSD upsampling - Which is better?

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What are the advantages and disadvantages of converting from PCM to DSD off-line vs. in real-time?


I'm talking from a qualitative listening standpoint, not a convenience or storage standpoint.


All other things being equal, would the sound likely be better through off-line conversion vs. real-time conversion?


If you have any experience with a particular software program, I'd be interested in having you note it in your reply.





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Doing such up conversion "offline" removes any glitches due to the intensity of processing required. Theoretically a more complicated algorythm could be used which would choke a processor trying to do it in real time. Online processing may also affect power supply lines which may contribute to a degradation of sound quality.





...in my opinion / experience...

While I agree "Everything may matter" working out what actually affects the sound is a trickier thing.

And I agree "Trust your ears" but equally don't allow them to fool you - trust them with a bit of skepticism.

keep your mind open... But mind your brain doesn't fall out.

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My Meitner's DAC chip is native DSD128, and therefore all sample rates are sampled to DSD128 in my DAC. I have tried several times to take non-DSD stuff and convert to DSD (Meitner does not currently accept native DSD128, ironically) and I've never heard one example where the offline is even 1% better..in some instances they are identical, but many where offline produces a slight to large sonic downgrade. This tells me either my Sony DSD Direct (or Audiogate) conversion is less quality, less effective than the Meitner's own, or that the last conversion to DSD128 inside the Meitner is the great equalizer (not meant technically of course). By the way, for DSD conversion the free (and no tweet needed) little Sony Direct app is fast and seems good (I've only done a few cuts). DSF only, but that is my format of choice anyway.


However, given Joel's caveat of "all else being equal" then I agree with Eloise. I'm simply saying all else is usually not. :)

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Ted -


Where did you get the DSD Direct app? The only versions I found online were "update" versions, and they won't install without an original version (apparently v1.0).



Main listening (small home office):

Main setup: Surge protector +>Isol-8 Mini sub Axis Power Strip/Isolation>QuietPC Low Noise Server>Roon (Audiolense DRC)>Stack Audio Link II>Kii Control>Kii Three (on their own electric circuit) >GIK Room Treatments.

Secondary Path: Server with Audiolense RC>RPi4 or analog>Cayin iDAC6 MKII (tube mode) (XLR)>Kii Three .

Bedroom: SBTouch to Cambridge Soundworks Desktop Setup.
Living Room/Kitchen: Ropieee (RPi3b+ with touchscreen) + Schiit Modi3E to a pair of Morel Hogtalare. 

All absolute statements about audio are false :)

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First, Ted, thanks for being such a consistently great guy.


Second, if your Meitner always upsamples to DSD128, I'm assuming you would have had to have heard upsampled files on a different DAC.


So I'd appreciate learning on which equipment you heard off-line upsampled files.



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I guess there are not many pieces of software that support both "online" and "off-line" ways, so comparing is hard.


For my own algorithms, software and hardware, I don't hear a difference between these two ways.


When I'm developing algorithms, I don't consider so much if it is possible to run it in real time on any particular hardware or not. If it doesn't run, then one needs to buy faster hardware. I only optimize it to run as fast as possible in ways that don't have impact on quality.

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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