How to address too much gain in DAC / power amp set-up?

[zydeco]

Too much gain. Yes, I’ve got the common issue of too much gain in my computer-based stereo system. The set-up involves ExaSound e18 DAC feeding power amplifiers that drive main amp with a full-range signal to Gallo Strada 2 speakers and a second amp that drives low-passed passive subwoofers. To get the volume manageable I’m introducing 30dB of attenuation within the e18 G3 DAC controller and then fine tuning with the digital volume control within JRiver. My understanding is that the volume control for the e18 is analogue in that it controls the output of the Sabre chip but I’m concerned that at this level of attenuation the signal to noise ration decreases. I’ve reached out to George to confirm the behaviour of the e18 but, if the above is true, then the options look to be a) reduce the gain in the power amplifier, b) add a fixed in-line attenuator (e.g., Rothwell), c) add a variable in-line attenuator (e.g., Seta Beta) or d) use a passive pre-amp / volume controller. The option of gaining the power amplifier gain seems the most correct but I’m open to ideas as to how to how to solve the problem.

 

[zydeco]

Really well designed dacs, such as Weiss, have variable analogue output, and a properly designed digital attenuator.
You just adjust the analogue output ,so the music can be as loud as you will ever need, and then just use the minimum of digital attenuation to adjust volume.
Keith.

Keith - Thanks. The e18 has analogue volume control which, as I understand it, sees the voltage output of the Sabre DAC adjusted and I'm using the mix of analogue / digital attenuation as you described. My concern (to be validated) is that SNR reduces at low volumes which has led me to the question of whether the best plan is to run the DAC at full volume and then insert a fixed in-line attenuators (e.g., Rothwell), run the DAC at full volume via a passive pre-amp or reduce power amp gain. I guess that another option might be to move to another DAC but, ultimately, this is one of the few multi-channel units which is useful when managing multiple sub-woofers.

 

[zydeco]

If you have an analogue volume control on the dac just use that, leave JRiver completely unattenuated.
Keith.

Keith - My concern with this approach is that the signal to noise ratio will be impacted given that the unit manages analogue volume via controlling the output voltage of the D/A chip. The maximum SNR is 125dB for the unit so if I need 40dB of attenuation before fine tuning with digital attenuation then that would go to about 85dB (which, I guess, is comparatively low but does seem high in the scheme of things). Is this a valid concern or am I missing something? - Zydeco