Digital gain vs analog gain


Is there a rule of thumb that guides the balance between digital input level, analog pre-amp input level and analog amp attenuation for reach your desired listening volume? 

128x128retrocrownfan

If my DAC has gain like my RME , I will experiment with the output voltage and set the volume to "0dB " on the DAC and use the preamp volume ,    

For most RCA installs I had that DAC set to +5 dBu and it put out about 2 v to my Preamp.    Set it too low and you invite noise by having to crank up the volume due to low gain.  Set it to high and you can overload the preamps inputs.   

If the DAC has no provision for adjustment,  I set set the volume to 0db.  If the volume does not read out in  - dBu , like "-99 through 0"  I will set it anywhere between "-10 and -3 " 

Understood. When playing streaming music from my iPhone I can control the final volume of listening by changing the output level of the app (which I assume is digital) or changing the analog output level on my Shiit pre-amp to my analog amp or change the amp attenuation.

I’ve running my old Crown at 100% but am wondering which of the other gain sources is best to maintain clarity of signal. As I understand things excessive gain in the digital realm creates clipping and excessive analog gain creates distortion. How can I avoid these pitfall?

…aaand, knowing just enough to be dangerous, it seems that too little gain can hurt signal to noise rstio?

Depends on the source. Being old school, I run the DAC at 100% up to my integrated amp, even though it has an analog volume control I could use.

I also use Roon for DSP correction though, and it does all the math at 32 bit precision so I could probably use it as a volume control as well without being able to tell any degradation in sound.

 

Digital volume control reduces resolution of the signal and is therefor depending on the original resolution of the audio file. With 24 bit you could  decrease the digital gain more than with a 16bit file  before you will lose resolution. As a rough rule of thumb  16bit files shouldn't be played with settings  lower than -10dB, 24 bit not lower than -20dB.

The analog volume control also does something "bad" to the audio signal. Normally it is a voltage devider circuit which shortens  some part of the audio signal to ground. Everybody knows that the volume control should be set at least around 11 o"clock or higher in order to get a good sounding signal at the output. The subtle information in the audio signal will suffer first if the analog volume control has to be set too low for comfortable SPL levels.

Ideally one would use a combination of digital and analog volume control: setting the digital volume control for full resolution of the digital signal and using the analog volume control as little as possible.

How effective one can combine these two settings depends of course also on the gain of the preamp, input sensitivity of the power amp, and sensitivity of the speakers. If everything lines up one could set the digital gain around -5dB, the analog gain to almost fully open and the SPL would be at 80-90% of full volume for loud listening.

There have been attempts to work around the neg. effect of analog volume control like putting the voltage divider after the input stage, using current instead of voltage control, or in the tube compartment one can use the 6386 (normally used in pro audio gear comressors)and control /adjust the gain instead of shorting a big amount of the signal to ground.