SQ impact of volume control before the preamp

I’m going to go out on a limb here, making an assumption. But given the serious audiophiles I’ve run into over the years using Squeezelite, I assume that many do not trust the SQ impacts of any volume control before the preamp, and leave everything but the preamp at 100% all the time.

Yes many audiophiles what to do volume control in the analog domain. The Roon implementation in the Sonicorbiter SE supports three different ways to do volume control None, Software , and Hardware.

Typically audiophiles are going to set this to none guaranteeing lossless audio all the way to the DAC. They use a preamp to control the volume.

The software setting does the volume control inside of the RAAT software on the device. The implementation uses a noise-shaped dither, and expands headroom to minimize the chance of losing information while attenuating.

The third method, hardware, sends commands over the USB bus to have the volume control done on the DAC.

How the DAC control volume is widely varied for example many cheap DACs are using some really bad methods for volume control.

But DACs like the Firefly are actually doing volume control in the analog domain, and many others have existing DSP that can incorporate attenuation without additional losses in quality.

In this case you need to know what to expect from your DAC.

We released Roon without support for software-based volume control adjustments because we are well versed in this line of thinking, and there isn’t too much controversy in the Audiophile world on this point.

And then we found that we were losing customers over it, since many people rely on it for convenience, especially in context of a whole-house audio/music solution.

And then we found that some hardware of the RoonReady products include it as part of their other offerings (for example, the Auralic Aries). It is important to us that RAAT offer parity with the other playback mechanisms on those devices.

So we decided to build the feature into RAAT. RAAT currently runs on RoonReady devices, but we are in the progress of replacing Roon’s existing audio infrastructure with it. This is what is enabling features like RoonSpeakers, zone linking, and software volume adjustment to reach a broader audience than just people who buy RoonReady hardware.

Software volume control is optional. Even when enabled, it is a pass-through when set to 0dB attenuation, and the quality light switches from “lossless” to “high quality” in real-time to reflect the presence/absence of DSP.

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Noobie/upgrade question along these lines - Running RoonBridge on a garden-variety little Windows box, I am able to adjust volume in Roon without (apparently) changing the signal path quality. Placing a Sonore ultraRendu box in place of the Windows/RoonBridge, making use of software volume control, seemingly, reduces signal path quality from Lossless to High Quality. (Same low-end DAC/amp in both cases.)

I wondered if the Hardware volume option on the Rendu might address this, but it seems to behave identically to the volume control Off setting.

Is this all as intended? Something different about the way volume control is implemented in these two cases?

Thanks for any insights.

Referring to our software volume control as “High Quality” is an editorial choice. It’s a perfectly well-executed dithered volume control with headroom expansion like most other high quality digital volume controls you’ll find in the industry.

However–doing that in software, instead of in the DAC, Amp or Preamp is usually less preferable to doing it further down the chain. So we mark it as High Quality to encourage better system architecture.

If the “Hardware Volume” option doesn’t work on the Rendu, that usually means that the DAC is not responding properly to USB Volume Control commands. This is not uncommon at all–many DACs incompletely or partially implement the USB volume control standards, unfortunately.

Thanks. Any way to evaluate whether the DAC is or is not implementing USB volume controls? A list of good and bad actors, perhaps? (That’s the likely next upgrade in the chain.)

There is this -

[0000048] 0.048 INFO [volume/alsa] initializing
[0000049] 0.048 TRACE [volume/alsa] [hw:0] Settings
[0000050] 0.048 TRACE [volume/alsa] [hw:0] mixer index: 0
[0000051] 0.105 TRACE [volume/alsa] searching for volume control element
[0000052] 0.105 TRACE [volume/alsa] card has element 0, Clock Source 12 Validity
[0000053] 0.105 TRACE [volume/alsa] (skipping: element doesn’t support playback volume)
[0000054] 0.105 ERROR [volume/alsa] couldn’t find mixer element

We record that information in our list of Roon Tested USB devices here: http://kb.roonlabs.com/Partner_Devices_Matrix

Obviously that doesn’t comprise every DAC on earth…but as far as USB DACs go, you’re looking for something with a Yes (and no footnote) in the USB Volume column.

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Got it. Cheers, thanks.