[ebag4]

I have determined that a direct connection to my amp(s) from my DAC yeilds the best sound in my system.  The issue I have is that I am running 16/44.1, using the volume control in MPD is likely dropping information at volumes less than 100%.  I believe the Squeezebox Touch is adding bits so that when the volume is reduced you don't loose information, are there PC based solutions that do this as well?

What digital volume control solutions are you using? 

Looking for recommendations.  My present system is:
NMT serving flac files over the network>Alix/MPD>Tranquility DAC>Split outputs to Bottlehead 2a3/Rythmic 370peq Servo Bass Amps(2)>GR Research V1s


Best,
Ed

[pardales]

Great question. I wonder if anyone is using Pure Music, or even iTunes for that matter, as their volume control direct to an amp (via a DAC of course)?

[JohnR]

I use Pure Music and go straight into my digital crossover. However to the OP, the 16-bit DAC is the limiting factor, there is no way to add extra information (that won't get lost at the DAC anyway).

[ebag4]

I use Pure Music and go straight into my digital crossover. However to the OP, the 16-bit DAC is the limiting factor, there is no way to add extra information (that won't get lost at the DAC anyway).

Thanks John.  I wasn't certain if the Touch would ramp it up to 24 bits for the volume control and only pass the 16 bits for audio with a 16 bit DAC or not.  Of course, attempting to use a USB DAC with the Touch may be a bit of an issue anyway.  I have read that you can modfiy scripts in Linux to allow it to do this, I wonder what the sonic penalty is when going this route?

Best,
Ed

[pardales]

Thanks John.  I wasn't certain if the Touch would ramp it up to 24 bits for the volume control and only pass the 16 bits for audio with a 16 bit DAC or not.  Of course, attempting to use a USB DAC with the Touch may be a bit of an issue anyway.  I have read that you can modfiy scripts in Linux to allow it to do this, I wonder what the sonic penalty is when going this route?

Best,
Ed

My understanding is that PM uses "dithering" in the volume control, and this prevents it from losing info as you control the volume. I don't know if this is right. The core issue is, if you use PM or iTunes (or some other software program) to control volume, do you lose info/bits? Perhaps it depends on which software program you are running as well?

[JohnR]

There are two issues, one is how much and the nature of quantization noise introduced in the scaling, the other is the resolution at the output. With a 16-bit DAC, it's the latter that is the main limiting factor. Never say never though - if the gain structure is set up optimally it might work well. Ultimately, you'd need to try it.

[Vincent Kars]

Volume control is multiplying the original bits e.g. by .5 to half the volume
As a consequence you lose resolution.
Because of the quantisation error dither should be applied in case of 16 bits.
With a 24 bit DAC the quantisation error is at -144 dBFS down so probably way below the noise floor of your gear.
However moderate digital volume control won’t do much harm.
A discussion on this subject can be found here: http://www.whatsbestforum.com/showthread.php?3813-Digital-Volume-control

[ebag4]

Volume control is multiplying the original bits e.g. by .5 to half the volume
As a consequence you lose resolution.
Because of the quantisation error dither should be applied in case of 16 bits.
With a 24 bit DAC the quantisation error is at -144 dBFS down so probably way below the noise floor of your gear.
However moderate digital volume control won’t do much harm.
A discussion on this subject can be found here: http://www.whatsbestforum.com/showthread.php?3813-Digital-Volume-control

Thanks for stopping in and commenting Vincent, much appreciated.  If I am understanding what is being said on your forum, I could get by with using the digital volume control in MPD if I listen at a fairly consistant volume that was not down by more than -10db.  In other words, if I set my system up so that my gain at the loudest I would normally listen was within 10dB of the maximum volume level I would experience very little loss of resolution.

While I am not quite there today I may try an FMOD or similar to reduce the gain a bit.

Thanks again.


What digital volume controls are you guys using, I am certain there are more of you using digital than have posted here.  Let us know what you think of your solution!

Best,
Ed

[gooberdude]

I've been using digital volume 100% the last few weeks.  This is only temporary, but works ok. 

Most of the time i use Pandora, MOG, Netflix or Pure Music.

My set-up is a mini/Tranquility Dac, Niteshade SET amp (this week, p/p next wk hopefully).

I'm set to receive an OptoCoupler preamp in a few days, and will compare to the direct connection.

Regardless of the 4 sources listed above i can't turn the volume up more than 20% from zero, this is my only gripe.  The Hawthorne Sterlings get crazy loud with 15wpc.  5wpc would do fine i'm sure & provide more range the volume.