dan saidI will try this tonight when returning from work.Why don't you try connecting your DS directly to your amp and power it down with the DS "muted," and tell us what you hear.;-)
Currently I am powering down my amps without muting the DAC, and the process is completely silent.
Dan says:
“I’m selling the DS because I have another DAC that sounds better in my system.”
Seems like time to move on, Dan.
dan said Why don't you try connecting your DS directly to your amp and power it down with the DS "muted," and tell us what you hear.;-)I run the DS directly into a large tube amp currently, and previously into a solid state amp. I'll swap back, or use another amp in a bit as I like to continue changing and evaluating.
Mute on the DS nicely works as a mute and I use it regularly; the sounds stops coming out, and everything gets nice and quiet. Weird, huh? 
The problem you are experiencing appears idiosyncratic to your choice of amp. Given the large number here who run the DS directly into an amp we would have heard of the issue long ago if it were a common problem.
dan said Does the mute function on any other piece of audio gear on the planet function this way?Yes, a number of products transmit and/or process digital black when muted or the volume is set to zero.
It is unfortunate you have experienced the problem. The good news the issue is rendered moot by your determination that another DAC sounds better to you.
Happy Trails!
I’m running direct to a Spectron solid state amp. No problems with mute, and it doesn’t seem to matter what order I turn things on or off… everything stays nice and quiet.
Frode saidI tried this tonight and the result was absolutely dead silence (using USB input from Aries).dan saidI will try this tonight when returning from work.Why don't you try connecting your DS directly to your amp and power it down with the DS "muted," and tell us what you hear.;-)Currently I am powering down my amps without muting the DAC, and the process is completely silent.
I’m glad to hear that the DS “mute function” works for others.
Put my other DAC back into my system, no noise when powering down when it’s muted, and there’s no hiss unmuted when I pause the digital input with my ear right up to my speakers.
With the DS there’s always a hiss coming from the speakers when I pause the digital input or hit the mute button.
I do not recall others complaining of a hiss and, of course, no one else has claimed problems with the mute function.
If you feel there is something wrong with your unit, I suggest disclosing this to potential buyers. Better yet, return it to PS Audio and let them take a look.
There was a report of hiss on another forum.
After talking with customer service and confirming how the DS mute function works, I don’t think there anything wrong with my DS, the hiss can’t be heard at the listening position.
I’ll bet anyone who has an amp with an input sensitivity of less than 1.5v, can hear the DS hiss with their ear close to their speaker.
It was good of you to remove that part of your post that previously claimed something was wrong with your DS and/or PS Audio’s QC was lacking.
My tube amp has an input sensitivity of 1.3V; SS, 1.25V. No hiss with either. Anyone else?
Link to the other forum complaining of hiss?
dan saidWith the DS there’s always a hiss coming from the speakers when I pause the digital input or hit the mute button.
The hiss is there at all volume settings and inputs on the DS, the mute function has no effect on outputs.
There’s no hiss with two other DACs I’ve connected directly to my amp.
BTW, in my experience bad grounds cause hum not hiss.
As I posted, you can only hear the hiss when you’re close to the speakers.
My amps have a sensitivity of 1VRMS (2.8Vp-p) - No hiss.
I too, have some hiss or noise being produced by the DS. I installed the kit in my Mark II two weeks ago. At first I thought it was tube noise, but then I realized it disappeared when the DS was turned off and my tube amp was left on. I hooked up a solid state amp and the noise was still there and the same character. It is very low in level and the DAC sounds very good. If other’s DSs are dead quiet however, perhaps I may have a problem and the performance of the DAC may be even better than I am hearing.
Welcome, Woolz!
Do you know the sensitivity of your amps and of your speakers?
It may be only a certain conspiracy of circumstances produces hiss.
Nothing is wrong with your DS, PSA knows about the hiss.
My amp is a Line Magnetics 518 integrated 845 SET rated at 200mv sensitivity (integrated). I am using the direct input though. But the noise is the same using the line stage or going direct. Speakers are Zu Def 4s rated at 101db sensitivity.
The high sensitivity of your speakers may be why you hear hiss and others do not.
Do hear any groundloop-like hum, or any other untoward noises?
There is no hum, just soft noise with a periodic very soft electronic squeal. I connected the analog outs of my Oppo 103 player to the line stage and also the DS through the line stage. The Oppo has similar character noise but significantly lower in level, but not dead quiet. What has impressed me is how quiet my amp is. Thanks for your input Elk.
Interesting stuff.
Your speakers would reveal every little thing. By the way, are they as wonderful as they say? I have read nothing but excellent things about them, but have no personal experienced with them.
So, you don’t think there is anything amiss with my DS, that the noise level is a compromise in the design that only shows up on very sensitive speakers? Hmm. In fairness I would say that the noise level would be within the bounds of acceptable from many a tube amp. Also, to return to topic, I might add that my mute works as it should.
The Zu speakers allow me to enjoy the glory of SET amp simplicity with the ability to go loud and low. They are an effective blend of compromises to my ear. I’ve heard them with a good range of amps and they sound best I think with the 845 tube. The first thing I played on them with a Sanders amp was Miles’ CD Milestones. After just the first cut I knew this was the way I wanted horns to sound and that was it. I just needed to find the right amp and I was pretty sure the Sanders was not it although it sounded excellent on the Dynaudio C-4s the Zus replaced.
I might add the DS is fed power from a P-10 through an AC-12.