Core Machine (Operating system/System info/Roon build number)
Mac Mini 6 core i7
Network Details (Including networking gear model/manufacturer and if on WiFi/Ethernet)
Playing from external hard drive connected to the core so network is not relevant here
Audio Devices (Specify what device you’re using and its connection type - USB/HDMI/etc.)
Classé new Delta pre-amplifier with DSD capable DAC
Description Of Issue
Input: DSD64 with EQ on
When I choose DSD output mode, it seems upsampling only occurs after EQ. But ideally EQ should be performed on already upsampled signal?
This seems so when I choose PCM output - bit depth is only downsized from 64 bit float to 24 bit after EQ. On the other hand, signal path shows the high rate 2.8M signal was downsampled to 384K before entering EQ, which might cause some loss?
Under such circumstance, I don’t know which setting is better . I reckon DSD output is better for original DSD music?
The crux of my question is if there is any hidden upsampling and downsampling process happening within the EQ work which is not shown in the signal path .
I’m hiding my uniformed response as a simple forum search (I should have done this) shows Roon explained this back in '17
I’m going to throw a guess here…
EQ only works on PCM. What you’re not seeing in the first path is a conversion from DSD -> PCM -> EQ -> new PCM -> DSD. I have no idea if there would be any benefit to converting upsampled DSD128 to PCM and then back again. When keeping DSD as the output format then it coverts the “native” DSD to PCM to hand to EQ which then hands it back to the DSD engine for upsampling. Again, this is a bit of a guess.
When you output PCM then DSD is converted to PCM first and the hidden path is 384k PCM -> EQ -> new PCM. So there is not conversion back to DSD out of the EQ filters.
Hi Ipeverywhere, thanks for the in-depth knowledge . I like your summary - probably EQ could be done only on PCM. If that is the case, it’s not a good idea to convert the signal back to DSD anymore. In that sense, my second setting (output PCM) might be better though the overall quality is green, not blue .
Sometimes , difference is not always audioable. How many people are able to tell from green to blue quality. EQ itself is a lossy process, so is DSD to PCM or PCM to DSD converting.
If iEQ is done on PCM and I choose DSD output, there will be too many conversions like this : DSD > PCM > EQ > PCM > DSD > DSD upsampling > USB.
On the other hand , if I choose PCM output, the path might be : DSD > downsampling to PCM > EQ > PCM > PCM downsampling > USB .
As such , knowing how EQ works is critical here .
I get your point from technical prospective. But would you listen to the better technical version on paper, or maybe just prefer what your ears like better? I know it’s not the answer to your specific question, just wanted to express that sometimes we (me included) are stuck in technical questions while the answer should come from somewhere else…
Then in this case IMHO it doesn’t really matter to get this answered, other than satisfying the analytical part of your brain (what on the the other hand could have influence to what you think you hear, human brainwork can be very complex…).