I’m getting different answers to this question online. If I connect the A6 through USB/coax/optical to an external DAC (with no volume control) to a power amp, will I be able to adjust volume through the A6? Some say it’s passthrough/fixed only. Others say it’s possible to adjust volume in the digital domain. Separate question: If digital variable volume is available in the A6, how much does this affect sound quality? ETA: My external DAC is a miniDSP SHD. It does have a streamer and volume control but I don’t use either because it has an ongoing issue with spontaneous volume changes in Roon. It’s just too risky for me to use aside from its DAC and multi-subwoofer integration ability. Sorry for the confusion in saying it’s a DAC with no volume control.
Yes you can, you have volume control for both digital and analog available on the A6. Just set the Volume Passthrough setting to OFF first, then adjust volume via the main rotary knob or via the App. Digital volume control will inevitably alter the numerical values of the audio samples, so if you attenuate a lot then there must be a corresponding loss of bits as you have much smaller numerical values to represent. So a loss of resolution must occur if you do this. I leave the Volume Passthrough to ON and so export digital to an external DAC at max 0 dB, then attenuate at the final preamp stage.
Thank you so much for your fast, thorough response. Since I'm unable to control volume with an analog preamp, how much will this loss of resolution affect affect sound quality? Is it analogous to the difference between hi-res and CD quality (this wouldn't bother me), or is it more like the difference between CD and lossy quality?
Difficult question to answer. If you have to attenuate a lot to get the volume you want, then the number of bits being used will indeed be much reduced compared to what is originally available, so more like your second scenario I suppose. However if not so extreme a case, then a better situation more like your first scenario. However you are doing this for a very pragmatic and necessary reason, so I would say don't worry about it too much.
I truly appreciate your help with this. It’s so hard to get clear answers to these questions online. I’d really like to get the best sound quality possible, as I’ve invested a lot into my power amp, DAC, subwoofers, and speakers. I know you said don’t worry about it too much but, if I’ll need to rely on digital volume control, is this (A6) device a poor option for me? Is there another way I can approach volume control here without degrading quality?
I wouldn't say the A6 is a poor device on which to exert digital volume control, not at all. The original firmware was a bit limited in this regard, a 15-step method, but the latest firmware is much more detailed than that. In the end, we all have to attenuate somewhere in the audio chain. Some people say leave the digital at full bore and therefore use the full input range of your DAC and maximise the S/N of that analog output signal. But then even if you attenuate at the end via say a ladder attenuator in the analog domain, then your signal will be reduced and inevitably the signal to noise will degrade. The language is different as no reduction in bits occurs but the closer you are going to the noise floor one way or the other. This is why people can spend a lot of money on a preamp to do the least damage. I think there is nothing too bad about digital attenuation as long as it is not very severe. So standard CD quality at 16bit offers 65K approx resolution levels. If we say attenuate by 10 dB or 1 order of magnitude, then the range of the digital numbers goes down by this factor, but we still have many thousands of resolution levels left to represent the reduced audio range. Our human audio ear brain system could perhaps at a stretch hear this effect, but I think the convenience and exact numerical alteration of this digital control method are worth the price. Doubtless there will be many opinions on this.
There is no loss of bits with a properly dithered digital attenuator , thirty years ago perhaps. Keith
You, my friend, are so generous in sharing your wisdom and time to assist me. I admittedly don’t understand all of this (my technical knowledge is quite limited) but you’ve given me plenty to research and consider. For now, I will take the chance and order an A6 to see how it works in my system. Thank you very much for all your help.
Thank you, Keith. I think I’ve seen your posts on ASR. Could you refer me to anything (posts, articles, forum discussions) that support this view, especially as it relates to the A6?
Get yourself the best DAC/Pre Amp in the market and digital volume control with loss of resolution is not your problem: https://rme-audio.de/adi-2-dac.html Happy listening!
Thank you for the suggestion. I updated my original post to clarify my DAC situation. I’m somewhat limited in the preamps/DACs I can use because I’m integrating two subwoofers, and I believe the SHD is quite good (aside from its fussy volume control behavior with Roon) and comparable in quality to the RME.
I have a miniDSP SHD Studio digital preamp which I use when I want to do Dirac room correction. It's inbuilt digital volume control is fine but I have not used it with Roon. So not including a DAC function like your SHD model but an all digital box. So if I am doing room correction, I go from DMP-A6 via USB into the SHD Studio with Volume Passthrough OFF, then out into an external DAC with usually a small amount of digital volume control applied by the Studio in addition to the Dirac filter stuff.
Oh wow this sounds very similar to my setup. If I’m understanding you correctly, you are then making volume adjustments (A6 volume passthrough off) in the A6–is that right? If so, are you noticing any sound quality degradation with the A6’s digital volume control? I suppose it’s hard to compare it to another option for volume control in the setup you described, but what are your overall impressions for sound quality?
May have got the setting of Volume Passthrough wrong i.e. swapped in message above. So when ON it will work at max fixed digital volume, when OFF it will permit Volume control on the A6.
No sorry for the confusion, I send out from A6 to the Studio over USB with Volume Passthrough ON so max Volume. But I then attenuate a bit on the Studio in addition to further analog attenuation down at the preamp, I find the 0.5 dB digital volume changes on the Studio very good and precise.
I see--so A6 (max volume) --> Studio (with some digital attenuation) --> DAC/preamp (analog volume control)?
Yep when doing room correction. I have found that after tweaking my speakers a bit in my room, that room correction is more optional than it used to be. So now I often just go direct into DAC from the A6 with just a touch of EQ in the A6 to cut down the bass a touch. Then on from DAC to preamp where the analog attenuation occurs. I oscillate between these two modes really. A halfway house is always to go through the SHD but with the Dirac filter turned OFF. So then just for convenience I will use its digital volume control as a fine control, most of the control is via the preamp analog or coarse control if you like.
