What is the "purest" way to lower/attenuate source volume in Roon?

I’m using Martin Logan Purity speakers, they are self-powered/amplified… so I need a volume knob. I suppose by your wording, it would be a “pure amp”. It’s not a pre-amp before an integrated amp.

Again, I was using the volume knob on my iFi Zen DAC but prefer to use the Parasound pre-amp for the remote but also because I want to use the “line out” (old tech TAPE REC output) to also split the audio signal to my Gilmore headphone amp (volume off on pre-amp but using volume on headphone amplifier when using headphones.

Can you adjust gain on the power amp section of the ML speakers? I’m not familiar with them. I sometimes use active speakers and that’s how I deal with this.

  • DAC set at 100%
  • Adjust power amp gain until pre-amp volume dial at 12 o’clock for normal listening

You can also use roon for digital attenuation as has been suggested but by the sounds of things you are using the pre-amp analogue inputs as well and probably want more integrated volume control.

From my experience it’s much better left out of the digital side and left to the preamp or DAC that has a decent preamp. In all my trials Roons DSP volume is lacking. Even Danny recommends analogue over digital for attenuation for best results.

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You got a source for that ?

I totally agree.

Ah, found it - @euge_lee, my wrong.

I read that from Danny and remember that I found it strange… I also believe a 64bit digital volume is better than any analog control where the potmeter is directly in the signal path. There are a few analog controls that keep the adjustment mechanism out of the signal path (I think Ayre did that) which is better.
Maybe some digital devices do not respond well to a attenuated signal input while others handle this good? I don’t know why that would be, but it could help explain why some ‘hate’ digital attenuation and others like it.

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Well, your preamp has gain and amplifies the input signal, that’s why.

But did you try to use the input labeled ‘direct’, as it’s advertised as being separately switched and just volume controlled; see excerpt from the manual:


That hopefully gets you better results.

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Surprising that this preamp reaches unity gain at only 20% on the volume dial. Maximum voltage swing is “> 10 V before clipping”, so I suppose that’s possible. the Zen DAC should be ~2 V at full swing from the single-ended outputs. Just seems like an unusual amount of gain for an analog preamp.

From the manual…

Yeap - plus balance problems at low levels and everything else… as I pointed out, I can totally see the caveats (fwiw, I had this, from John Siau, in mind when I posted - AFAICT, in this particular case, all the conditions are met with an unknown in terms of analog gain):

DSP-BASED VOLUME CONTROL CAN WORK WELL PROVIDED THAT THE FOLLOWING CONDITIONS ARE MET:

The digital volume control must be properly designed. The DSP calculations must internally use word-lengths of at least 24-bits. If the output word length is less than 24-bits it must be dithered. either be dithered or long word-lengths (24 or more bits ) must be delivered to the D/A converter. Many media players, computers, and digital devices use 16-bit undithered volume controls. In most cases, these 16-bit volume controls can bypassed by setting the volume to maximum. When this is done, an external D/A converter can be used to control the playback level.

The D/A converter must have a spectacular dynamic range. It is not uncommon to require 20-30 dB of attenuation for normal listening levels. In those cases, the dynamic range of the D/A will be reduced by 20-30 dB. If your D/A converter only has a 110-dB dynamic range, the output will have a dynamic range of 80-90 dB – a dynamic range that is less than that of a 16-bit CD.

The peak level of the D/A converter’s output should match the maximum input level of the next device in the signal path (amplifier, pre-amplifier, etc). This is a fundamental part of proper gain-staging, as it fully utilizes the headroom of both devices. This is the reason that professional audio facilities will standardize the operating signal level between audio devices (usually at +4 dBu at -20 dBFS). With this type of configuration, the dynamic range of the amplifier will usually be the dominate noise factor.

Maybe if @danny has a bit of time for this, he can further explain his answer…

I’m not familiar with the Parasound you own so I’ll ask a question. Can you adjust the volume between sources in setup on your preamp? My streamer is set to fixed volume so I have reduced the volume by -4db on my preamp to make the volume about the same for the phono input. Good luck.

No, the Martin Logan speakers do not have any sort of gain setting.

Yes, Direct is the input I am using…

Sadly no, the Parasound pre-amp is a well-designed and quality pre-amp… but basic as well in that it doesn’t have input level gains.

Yeah, the iFi DAC has horrible low level balance issues, I much prefer it set at “fixed” volume but now I must deal with the very sensitive pre-amp.

I think because of the fact I’m using DSP regardless for convolution and HAF filters… perhaps I should keep it simple and just consider DSP a foregone conclusion and just use headroom adjustment. I suppose I could have HAF build in attenuation in the filters but my concern there is if I turn off convolution (for whatever reason, like A/B test for with and without convolution) I could have a HUGE jump in volume. I’m looking at around a 21db attenuation right now to get my desired result.

Without diving into the specs could it be the iFi may not be “unity” at 100%? Meaning, at 100% its actually providing gain? This is common on any pre-amp so daisy chaining pre-amps can increase the signal as you’re describing. I would try and identify where on the iFi unity is. That is, where the input signal level matches the output level. That might be closer to 70%. In that case it’d be better to leave the iFi at that setting instead of fixed.

Well, with volume at 100 and flipping back and forth between fixed/variable… no change in output volume so I think I can assume fixed = unity.

Are you using the SE outputs or the balanced output from DAC to your pre-amp?

I’m using the RCA jacks on the back of the DAC. Pre-amp doesn’t have balanced inputs.

Now that’s strange, because IFI specs imply 2.1V in fixed output and 3.3V in variable @ 100%


Since the IFI potentiometer balance seems to be a problem, your solution may be building your own voltage dividers with resistors inside cinch connectors…