Originally I was using my iFi Zen DAC directly connected to an amplifier, therefore using the volume control on the DAC.
Recently, I decided to add my Parasound P/LD-1100 pre-amp (mostly because I wanted a remote control volume solution from my main listening position). So in setting the DAC to “fixed” volume, it works as expected but… what was 100% volume when not using the pre-amp… I now get with the preamp at 20% of full volume. This obviously makes “fine tuning” of volume quick difficult, especially with the remote.
I’m a bit confused as to why the preamp makes things so much louder but regardless, I want to attenuate the volume (source) so I have more control over volume in my listening room.
Options include: (please add another if I forgot one)
Go back to “variable” on DAC and lower it 50% (don’t love this idea)
Use DSP “Headroom Management”
Lower the gain levels in the convolution filters that I use
Avoid digital volume if you want the best quality as your decimating the bits which ever way you try. Stick with analogue and use your main amplifier volume unless this is a pure poweramp then you would need a preamp or attenuator before it. Adding a pre to an intergrated amp will give you two pres in the chain and you’ll be fighting volume issues which is not the best way to do anything and you have to sources of attenuation to the signal possibly adding more noise. So just get up and use the volume on the amp if it has no IR or change it for one that does. Volume is always best controlled in the analogue domain for purity.
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.
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.
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.
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.
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.
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.