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  1. #11
    Senior Member pablolie's Avatar
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    I am just using digital inputs on the DAC2HGC, one comes from the TV, the other from the SB Touch. The Becnhmark indeed acts as both a DAC and a preamp, and feeds into the NAD M22 power amp. The DAC2 also has internal an internal attenuator, which I set to -20db. That allows me to keep the Benchmark volume set around the 11am mark.

    I keep the Benchmark around that 11am volume mark for the following reasons:

    * It is recommended by Benchmark for optimal sound quality.
    * Higher than that the (fixed) Toslink output from the TV is LOUD. given my config I like to match things a bit.
    * It allows me to control the volume for music -which really is my utmost priority- with the Touch, from the 30s (nice mellow alarm volume in the morning) up to typically 80-something for immersed listening (good volume, not too loud), depending on the sound engineer's loudness choice.

    Thanks gents!
    ...pablo
    Server: Virtual Machine (on VMware Workstation) running Ubuntu 18.04 + LMS 7.9.1
    System: SB Touch -optical-> Benchmark DAC2HGC -AnalysisPlus Oval Copper XLR-> NAD M22 Power Amp -AnalysisPlus Black Mesh Oval-> KEF Reference 1
    Other Rooms: 2x SB Boom; 1x SB Radio; 1x SB Classic-> NAD D7050 -> Totem DreamCatcher + Velodyne Minivee Sub
    Computer audio: workstation -USB-> audioengine D1 -> Grado RS1/Shure 1540

  2. #12
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    Reality Check Time. Agonising over where it's best to apply volume control is basically a waste of time and effort.

    An audio playback system has a fixed amount of gain. It also has a fixed amount of noise. For any given desired listening level, you need to reduce the signal level such that the fixed amount of gain gets you the playback volume you want. While lowering the input level reduces the playback volume of the wanted signal, it doesn't reduce the noise, which remains fixed. It really doesn't matter whether you reduce the input signal level in the digital or analogue domain. The result to all intents and purposes is exactly the same - as you turn down the volume, the S/N ratio gets worse.

    If you reduce the volume digitally, the least significant bits of resolution (ie. lowest level of detail) disappear into the digital quantisation noise. If you reduce it in the analogue domain, you also lose the lowest level of detail, which disappears into the analogue noise floor.

    The only difference is that by attenuating digitally, the intrinsic noise of the DAC becomes more significant, which doesn't happen if you keep the digital signal at 100% and instead increase the analogue attenuation. BUT: the linearity and noise floor of any modern competent DAC is so low it's really just academic. The noise in the rest of the system will swamp it. You'll never actually hear the difference under normal listening conditions.

    So in conclusion: unless you've got an insane amount of gain in the system, you won't hear a difference between digital and analogue volume control.
    Transporter -> ATC SCM100A

  3. #13
    Senior Member pablolie's Avatar
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    Quote Originally Posted by pablolie View Post
    I am just using digital inputs on the DAC2HGC, one comes from the TV, the other from the SB Touch. The Becnhmark indeed acts as both a DAC and a preamp, and feeds into the NAD M22 power amp. The DAC2 also has internal an internal attenuator, which I set to -20db. That allows me to keep the Benchmark volume set around the 11am mark.

    I keep the Benchmark around that 11am volume mark for the following reasons:

    * It is recommended by Benchmark for optimal sound quality.
    * Higher than that the (fixed) Toslink output from the TV is LOUD. given my config I like to match things a bit.
    * It allows me to control the volume for music -which really is my utmost priority- with the Touch, from the 30s (nice mellow alarm volume in the morning) up to typically 80-something for immersed listening (good volume, not too loud), depending on the sound engineer's loudness choice.

    Thanks gents!
    I should note the following about the Benchmark DAC2 - the digital system never passes any analog volume control:

    ".. The DAC2 combines active analog gain control, passive low-impedance attenuators, a 32-bit digital gain control, and a servo-driven volume control. All inputs are controlled by the rotary volume control. This volume control moves in response to commands from the remote control. Analog inputs are never converted to digital, and digital inputs never pass through an analog potentiometer. Digital inputs are precisely controlled in the 32-bit DSP system. The DSP system preserves precise L/R balance, and precise stereo imaging, while avoiding any source of noise and distortion. .."
    ...pablo
    Server: Virtual Machine (on VMware Workstation) running Ubuntu 18.04 + LMS 7.9.1
    System: SB Touch -optical-> Benchmark DAC2HGC -AnalysisPlus Oval Copper XLR-> NAD M22 Power Amp -AnalysisPlus Black Mesh Oval-> KEF Reference 1
    Other Rooms: 2x SB Boom; 1x SB Radio; 1x SB Classic-> NAD D7050 -> Totem DreamCatcher + Velodyne Minivee Sub
    Computer audio: workstation -USB-> audioengine D1 -> Grado RS1/Shure 1540

  4. #14
    Senior Member Mycenius's Avatar
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    Quote Originally Posted by pablolie View Post
    I have a rather high powered amp. If I turn the Benchmark DAC2 to 100% volume the SB Touch can't play at more than 55. I tend to keep the DAC2 at 50% and that allows me to crank the Touch volume up to 80 (that's entertainingly loud but not annoyingly loud), but typically more like 72. Do those setting impact sound quality, in your opinion?
    Quote Originally Posted by schiff1108 View Post
    There is even a set-up in LMS (Volume control) to keep the volume always on 100%.
    FWIW IMO You should never use digital volume control unless as a last resort - as @schliff1108 says enable the fixed 100% volume setting in LMS for the Touch (to disable it's digital attenuation) and use your DAC's volume control if necessary (assume this is digital anyway - but always best to do attenuation at the last point in the chain not the first to minimise flow on artefacts from it). To the best of my knowledge digital volume control effectively drops 'bits' of resolution for each step of db attenuation - so hence why its not ideal and can be noticeable at extremes (i.e low or high volume levels well away from the original recording's playback level).

    EDIT: and some good points by @cliveb in his post above, further to this - however IMO doing digital volume control last in chain is best "IMO" as I said above.
    Last edited by Mycenius; 2020-03-12 at 13:39. Reason: Added EDIT
    Hi-Fi 1: QNAP HS-453DX NAS+QLMS/Allo USBridge Signature+Shanti LPS/Cirrus ESS Sabre 32-bit Reference DAC (Oppo 105D)/Yamaha Aventage CX-A5000/Focal SM9s.
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  5. #15
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    I kind of agree in practise, but I would like to unpack what I see as the real problem.

    There is more benefit than downside with digital VC, if correctly implemented (low distortion and dithered). It's possible with SoX.

    There's another requirement, that the attenuation is moderate (I say -30dB to -10dB normal range). I'll discuss this toward the end!

    With several popular DACs, the ASRC and upsampling stages NEED digital headroom to perform correctly with highly dynamically compressed music i.e. most modern music! https://forums.slimdevices.com/showt...l=1#post747509. That means they need digital volume control (unless they have digital headroom built in specially like the BM DAC2/3).

    With these DACs, you simply won't be able to enjoy many modern recordings to the same level without digital attenuation. Here's a visualisation of the difference on a modern recording (inter-sample overs clipped vs not-clipped): https://www.pinkfishmedia.net/forum/.../#post-1990168. -6dB is always enough.

    People with smart phones, sound bars, mini/micro-systems etc. are actually better off in this way, because digital VC is built into these devices. I wouldn't be surprised if this was a big part of many audiophiles' complaints of modern recordings. Obviously there's damage done by dynamic compression that can't be fixed, but why add extra damage unnecessarily?

    Many DACs these days are hot via XLR - 4VRMS, some 6 or 8 - and if the DAC is being used preamp-less, this leads to excessive digital attenuation. Which is bad. Or necessitating the use of XLR attenuators, which I would argue is also bad. But Weiss have the ideal approach with a mixture of reference voltage adjustment in the analogue domain for coarse adjustment - so the XLR output level can be adjusted to 2VRMS (typical RCA output level) or even 1VRMS - followed by dithered digital volume control. All this without need for XLR attenuators. Also dCS do well in this regard. So I'd say dithered digital volume control brings many more benefits than downsides as long as the attenuation is moderate - and the problem is the design of many DACs with too high an output level to be used optimally when preamp-less.

    The reason the output levels are creeping up is that it makes it easier to achieve a better SNR/THD+N measurement, which people slavishly follow e.g. on ASR. It's a pity manufacturers are chasing one number to the harm of certain use cases e.g. using the DAC preamp-less.
    Last edited by darrenyeats; 2020-05-16 at 03:16.
    Check it, add to it! http://www.dr.loudness-war.info/

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  6. #16
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    I was always hearing that it is the best to do attenuation at the last point in the chain. Hence, I have tested some while ago In-Line Attenuators between the preamp and the power amp. Have tested different set-ups and I am very satisfied and continue to use them.
    Actually, I listen to music at 12 o'clock with all the known benefits.
    Here to read: http://www.rothwellaudioproducts.co....tenuators.html
    My attenuators were built by a friend.
    Living Room: piCorePlayer 5.0.0 on rPi 3B+ & Allo DigiOne & 1TB USB (LMS 8.0.0 & Squeezelite) & Keces DC-116, Mutec MC-3+ Smart Clock, Rega DAC R, Rotel RB-1070, Rotel RC-1070 or Fezz Titania Signature, Klipsch Forte III
    Bedroom: Boom / Workspace: Boom / Kitchen: Radio

  7. #17
    Senior Member pablolie's Avatar
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    Quote Originally Posted by schiff1108 View Post
    I was always hearing that it is the best to do attenuation at the last point in the chain. Hence, I have tested some while ago In-Line Attenuators between the preamp and the power amp. Have tested different set-ups and I am very satisfied and continue to use them.
    Actually, I listen to music at 12 o'clock with all the known benefits.
    Here to read: http://www.rothwellaudioproducts.co....tenuators.html
    My attenuators were built by a friend.
    Thanks - I just ordered some Rothwell balanced attenuators.
    ...pablo
    Server: Virtual Machine (on VMware Workstation) running Ubuntu 18.04 + LMS 7.9.1
    System: SB Touch -optical-> Benchmark DAC2HGC -AnalysisPlus Oval Copper XLR-> NAD M22 Power Amp -AnalysisPlus Black Mesh Oval-> KEF Reference 1
    Other Rooms: 2x SB Boom; 1x SB Radio; 1x SB Classic-> NAD D7050 -> Totem DreamCatcher + Velodyne Minivee Sub
    Computer audio: workstation -USB-> audioengine D1 -> Grado RS1/Shure 1540

  8. #18
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    Quote Originally Posted by pablolie View Post
    Thanks - I just ordered some Rothwell balanced attenuators.
    Pls report about your experience.
    Living Room: piCorePlayer 5.0.0 on rPi 3B+ & Allo DigiOne & 1TB USB (LMS 8.0.0 & Squeezelite) & Keces DC-116, Mutec MC-3+ Smart Clock, Rega DAC R, Rotel RB-1070, Rotel RC-1070 or Fezz Titania Signature, Klipsch Forte III
    Bedroom: Boom / Workspace: Boom / Kitchen: Radio

  9. #19
    Junior Member fastfwd's Avatar
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    Quote Originally Posted by pablolie View Post
    Thanks - I just ordered some Rothwell balanced attenuators.
    If you're using the DAC2's XLR outputs -- and if the DAC2 works like the DAC3 that I'm familiar with -- you can just open the case and move a couple jumpers to attenuate those outputs by either -10dB or -20dB.

    EDIT: Never mind, I see that you are already using the internal -20dB pad.
    Last edited by fastfwd; 2020-07-18 at 15:21.

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