Digital Attenuation


There is a thread on another forum that claims the DirectStream digital attenuation lowers sound quality. Here is the thread link:

Here is a quote from one post:

“The DirectStreams (both Jr and Sr) are considerably noisier than most other DACs as a result of their single bit designs with digital switches in the output stage. This makes digital attenuation for the DirectStreams especially problematic as the available range is severely limited. The designer, Ted Smith openly acknowledges the issue and attempted to work around it by providing a relay that attenuates the outputs 20db by adding a shunt resistor to ground. Enabling the relay lowers both the signal and noise floor by 20db, while digital attenuation only lowers the signal. In practice, even the attenuator workaround wasn’t sufficient with my DirectStream Sr (6db quieter than the Jr) as more than a couple db of digital attenuation still degraded sound quality. I ended up using a number of passive preamps of varying quality, any of which were more competent than the digital attenuation. FWIW, Ted uses an external preamp himself.”

Are these posts off base?

I thought the digital volume control was lossless? They’re claiming that “bits are lost”, but I’m pretty sure that Ted has mentioned that his volume control is lossless. Also, isn’t the resister a passive (analog) way to lower the noise floor? Ted has also mentioned that he believes it does not alter sound quality or at least in any audible level.

In my experience, yes, off base. I use a BHK pre after the DS. I cannot hear any degradation if I use the DS volume control. Perhaps the BHK masks it but I don’t think so.

Off base? not necessarily. But if your system is relatively level balanced and the DS sounds good at 100, it will still sound good at 50. That’s not the same as a system that isn’t as well level balanced where you can never turn the DS up to 100 for comfortable listening. With the 2nd system you’ll have more noise because you are running at a lower output level which may or may not be apparent. The volume control is still completely lossless but you’ll be operating the DS nearer it’s fixed noise floor.

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Ted, you are a humble man. I still stay its off base since the ‘problems’ called out apply to any DAC, not specific to the DS.

Perhaps the author/critic should have made his/her comments regarding DSD and not the DS specifically. Still it seems a stretch or there’s an agenda behind the comments. My DS, in my system, is considerably quieter than my former Oppo 205, and sounds way better to boot.

‘The makes digital attenuation for the DirectStreams especially problematic as the available range is severely limited’.

How does he/she figure this?

He does have a point in that DSD DACs are different than PCM DACs, he is correct that you’ll notice the difference more if you always use a low level on the DS’s volume control. Still, how he expresses things isn’t entirely even handed/neutral: I don’t see a lot of care to make neutral posts on the net :slight_smile:

I think there is an issue that many seems to think a digital volume control is a complete replacement for a good preamp. It’s not. Tho the DS’s volume control is lossless, running systems without level matching will always be a problem. With system level matching the DS’s noise floor isn’t a problem and is as quiet as the noise floors of many systems used to master SACDs…

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How do I know if my system is or isn’t well level balanced?

I have my maximum volume level set at 100 on the DS and find I’m listening in a range of from 58 to 90 with my attenuator set on low. Is this volume range optimal for getting the best sound quality?

That sounds fine. There are people who never get above, say 50. Some don’t seem to know what the 20dB attenuator is for. I need to keep my preamp way down and/or the DS way down. I think many systems can benefit from a good preamp, but there are certainly many systems out there that sound good without one. The thing is that you shouldn’t have to have to put up with noise and that there are multiple things that can be done.

My DS is front-ended by a good preamp, the BHK. From time to time, I’ll switch the attenuator on and crank up the pre. Both sound quiet, but the character of the noise is slightly different. I think the DS attenuator off, level 100, sounds a bit more dynamic but it could be that my comparisons aren’t level matched so the louder sounds, well, louder. Or that it level matches better with the BHK.

I enjoy these practical and thought experiments nearly as much as listening to music; only because I’ve recently in the past 9 months completely rebuilt my system to fit my smaller house. 6 months from now, I’ll be totally lost only listening to music and focusing/obsessing on something else in my life of hobbies. :wink:

For those of us without a pre-amp, the attenuator makes a huge difference. I can’t hear any of the noise with it in place.

A -20dB difference. The amp(s) and speakers make a difference too.

I guess I’m a lucky one. I have never heard any noise out of my DS Sr. Attentuator in or out, BHK pre or Pass Labs pre, no pre, no matter what, no noise, no hiss, no clicks, just music.

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What amp and speakers do you use?

right now I’m using a First Watt J2 amp…don’t get me started how much I love this amp… and DeVore 096 speakers which are on long term loan while my friend is working abroad. I also have some Zu Audio Soul Supremes on order. I’m a big fan of Zu Audio. I had some Zu Omen 2, Dirty Weekends that I gave to my son.

Ditto but with the Jr. Never a peep- just sweet and gentle Deep Purple and BTO :sunglasses:

Attenuator in or out, my DSsr is dead silent running straight (xlr balanced) into Audio Research Ref. 75 SE poweramp, no matter where i set the DS volume control. Dito with Audio Reseach Ref. 6 pre in place, SQ wise by far my favorite (usually with attenuator out and DS volume set to 80). Speaker is Martin Logan Spire.

I’m using ARC as well,albeit a bit older than yours. (Ref 6 = nice!) Never a issue. Attenuation out and DAC at 98. This gives me background at level 2, nice at 15, loud at 30 and ridiculous at 40+…

It’s not so much luck as it is circumstance and setup. Most users of our DACs have zero problems with noise. It’s why we sell thousands of them and make people so happy. We read about the outliers with problems because most of the people happy with their systems don’t post on the forums. I am not ignoring the issue that on occasion there’s a situation that isn’t working, but on the whole the vast majority of our owners are enjoying the hell out of our DACs.

The forums are like the newspapers. If you read the papers or listen to the news you’d conclude the world was falling apart at the seams, that chaos on collapse are right around the corner. And then you step outside into the real world and see none of it. Everything seems normal. This is because newspapers cull through the ordinary to single out the occasional extraordinary to fill their pages.


I own an integrated only (McIntosh MA6600). Leave my DSjr always on 99 and if needed work with the integrated’s remote. Is this a practice that you would recommend or not? And, should I use the 20 db attenuator or not? Speakers are Diapason Astera bookshelf.


You’re not hurting anything with the attenuator in or out nor with any particular setting of the DS volume control. In general people will prefer the higher settings on the DS’s volume control (tho there’s no practical difference between 100 and 99.) I use which ever remote is handy as the mood suits me. If you happen to like the sound better with the attenuator in and the preamp turned up to compensate, that’s fine, but I think fewer people would take that path.