I posted earlier about my DacMagic 200m not having volume controls. I’d rather not use Roon DSP volume and degrade the signal and get the high quality green dot.
So I tried adding HQplayer and it’s volume control and it changes Roon from lossless to enhanced with the silver dot.
Is this better than Roon’s DSP volume?
Whether you use HQPlayer or Roon for volume, the signal path won’t be lossless (or “bit-perfect”) anymore. That doesn’t necessarily mean the quality is reduced though. DSP volume control is very straightforward to implement, no secret sauces, and since Roon is using 64bit floating point samples for DSP, I can’t see how you could get better results with other implementations. Moreover, Roon’s volume control was measured and proved to be as good as it can get. So, if you just need volume control, you don’t need the additional expense of HQPlayer.
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What matters for the output quality is dither/noise-shaper used for the output data. Since no DAC will take in 64-bit floating point samples, the output precision needs to be limited to what the DAC can do…
When you are upsampling, the increased sampling rate combined with noise-shaper helps you maintain dynamic range in audio band compared to the original data, since the digital noise floor in audio band can drop tens of dB’s. HQPlayer offers you several different dithers and noise-shapers to choose from.
So if you use digital volume control, you should at the same time run upsampling to the maximum input rate your DAC can do and possibly utilize noise-shaping as well.
Even with plain TPDF dither and upsampling, every increase in sampling rate will drop the audio band noise floor.
If you are already using HQPlayer, then Roon will control HQPlayer’s volume instead of performing it’s own DSP.
Correct. However, virtually all DACs take 24bit samples, and, as I said before, there’s no need to dither 24bit samples since quantization noise is at -144dB. Nobody can hear that and no DAC can match that performance anyway.
@Markus_Menasci, you can take a look at the signal path to see the actual bit depth that is passed to the DAC.
I’m not going to go to endless arguments about who hears what. But with a good DAC there’s no trouble measuring the quantization distortion on 24-bit data if it’s not properly dithered.
Truncation is just ugly. No reason not to do a proper dither or noise-shaper, also for 32-bit output.
That should be OK if you are happy with how those algorithms sound.
I’m just playing around with upsampling
So my Dac has volume but it doesn’t work with Roon. Can’t Cambridge release a firmware update or something? Too bad they never answer a phone or return a message.
What is bettter…
Option (1) is safest, no surprises, less prone to accidents. Depends then on your preamp implementation, but it will hardly beat a digital one.
Which ever software volume control you use, take into account that the DAC shouldn’t be the default audio output device for the OS. So that you don’t accidentally get loud notification sounds or something like that. So there are some potential accidental cases for nasty surprises.
For (2) and (3), I of course certainly have my opinion, but I leave it up to you to decide.
Regarding (4), it is likely lower quality than (2) or (3), but possibly higher quality than (1).
Let’s not forget about DSD, which can’t be properly dithered. If that’s fine, then 24bit and 32bit truncation is also fine. No DAC can currently resolve more than 22 bits.
Not the right place to ask, and I do not know if I’m correct. Doesn’t software volume break the DSD? I remember this in roon, same for HQP?
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Yes it can, I have implemented it myself. It can beat 32-bit PCM in 100 kHz band… 
Yes they can. You are now talking about dynamic range.
No, HQPlayer has SDM DSP pipeline for processing SDM → SDM paths as well, with all the same DSP that is available for PCM sources.
So controlling volume with the Preamp knob/remote is the lowest quality? I figured it was the best since Roon and Dac volume would be fixed.
Roon dsp volume is better than the preamp knob or the Dac volume knob? I figured it was the worst.
It’s been demonstrated mathematically that it’s impossible to quantize to 1 bit and completely decouple quantization noise from the signal. I’m not sure why this keeps coming up.
Same way as if you have 2-bit signal and never go above -6 dB level.
No, a 2-bit signal doesn’t have constant power, like a one bit signal. Here we go again…
Usually all analog volume controls add noise and distortion.
How did you reach this conclusion? Not that there would be anything wrong doing that.
DAC volume knobs usually control DAC chip’s digital volume which is very rudimentary implementation.
You obviously don’t understand since you think DSD like 1-bit PCM, instead of PWM.
Look at all the class-D amplifiers on the market and try to understand how those are “dithered”.
I don’t know why you started talking about DSD. Of course, he could also run his DAC at DSD512 and likely get even better objective performance out of it. But I wasn’t the one to bring up DSD in this scope.
