[Craig T]

I'm usually in the mid-70s with HD650s in HP mode.

 

[pyro_dragun]

If you install the custom drivers, are you required to run in USB class 2 mode? I have heard that class 2 doesn't sound as good as class 1 for whatever reason, due to aliasing and the USB on the computer not being able to handle sample rates of the device running in USB class 2 audio mode.

 

[Magick Man]

I'm amping the hd600 with the grace m9xx, i have to turn the power up to 80 and above to drive it loud enough, is this the same case with everyone else, and i have it in high power mode as well.

Something is very wrong, I don't even need that much to drive my HE560s. Something must be off with your source level.

 

[Delance26]

If you install the custom drivers, are you required to run in USB class 2 mode? I have heard that class 2 doesn't sound as good as class 1 for whatever reason, due to aliasing and the USB on the computer not being able to handle sample rates of the device running in USB class 2 audio mode.

Yes, all you have to do is witch it on the device settings.  Super easy.  I will mention though I think USB 2 sounds better.  Seems to have more air to it, but maybe that is just me!
 
Cheers!

 

[John Q Lin]

I'm running with both usb connected. on my hd600 I need 80 on the volume nub to be loud enough. 85 is where I like, 90 is too much. is everyone using about the same volume setting. my streaming simple rate is 44, what about dac filters which one are you guys using F1? F2? F3? F4? also running on usb2 mode.

 

[Delance26]

Here is my review on the m9XX! enjoy, comments/opinions welcome!
 
 
http://www.head-fi.org/products/grace-design-m9xx-compact-usb-dac-with-integrated-headphone-amp/reviews/15592​

 

[Michgelsen]

  I have not had this issue with my m9xx at all.  I use the USB class 2 primarily.  I would contact Grace Design or Massdrop.  It could be a defect.

 
 

Mine is also dead silent on sensitive Grado cans using any of the input modes available. I have a power line filtering device on my PC's power supply though, too.

 
 

  The only time I can really hear any sort of background noise is on sensitive IEM's, which becomes negligible once music is playing because it is impossible to discern the noise than.  One thing I have noticed (while using sensitive IEM's) is that when you mute the m9xx you will hear an audible hum, furthermore it seems to disappear when the screen is dimmed, assuming you use the dimming feature.  The humming will not disappear if you do not use the dimming feature.  This seems to indicate that the screen is some how causing this noise and it is slightly concerning and I am wondering if any others have experienced this.  Again when music is playing it cannot be heard so it goes away (tested it with quiet tracks). 

 
Thank you both for the input. I only use usb 2 mode, and have display dimming enabled. The other day I couldn't hear the noises, but it was in the afternoon when it's not as quiet as during nighttime. It's not hum, or white noise; the noises are faint, intermittent and clearly related to activity on the computer.
I don't have IEMs or a dynamic headphone to test things with, but with the external amp/headphones connected I listen between levels 40 and 60. I'm not sure how sensitive that means it is, but the noises are clearly very faint, and it could be that many people simply don't hear them with less sensitive headphones. A difference of 10dB would probably make them inaudible already.
 
I will try and listen to it again, and also test whether I can hear a difference when the display is on or off. I'll contact Grace if the problem persists.

 

[fjrabon]

Thank you both for the input. I only use usb 2 mode, and have display dimming enabled. The other day I couldn't hear the noises, but it was in the afternoon when it's not as quiet as during nighttime. It's not hum, or white noise; the noises are faint, intermittent and clearly related to activity on the computer.
I don't have IEMs or a dynamic headphone to test things with, but with the external amp/headphones connected I listen between levels 40 and 60. I'm not sure how sensitive that means it is, but the noises are clearly very faint, and it could be that many people simply don't hear them with less sensitive headphones. A difference of 10dB would probably make them inaudible already.

I will try and listen to it again, and also test whether I can hear a difference when the display is on or off. I'll contact Grace if the problem persists.

Have you tried using the m9XX in USB class 1 mode? I've read instances where some computers have an issue with class 2 USB drivers causing static.

 

[Solarium]

For those who own both the m9XX and the iFi iDSD Micro, would you please do a quick comparison here? I'm mainly interested in their power output driving T1 or HD800.

 

[Angular Mo]

Any idea when there will be another Drop for device?

 

[Delance26]

  The only time I can really hear any sort of background noise is on sensitive IEM's, which becomes negligible once music is playing because it is impossible to discern the noise than.  One thing I have noticed (while using sensitive IEM's) is that when you mute the m9xx you will hear an audible hum, furthermore it seems to disappear when the screen is dimmed, assuming you use the dimming feature.  The humming will not disappear if you do not use the dimming feature.  This seems to indicate that the screen is some how causing this noise and it is slightly concerning and I am wondering if any others have experienced this.  Again when music is playing it cannot be heard so it goes away (tested it with quiet tracks). 

A few days ago I notice a humming issue with my device. Because I was curious I emailed Grace Design.  The response I got back was this:
 
"When the device is muted, the display uses a PWM scheme to make the
screen pulse. The noise you are hearing is a by-product of this. This
noise is usually only heard on very sensitive headphones like IEMs. When
the unit is un-muted, there should be no noise caused by the display.
This is normal behavior and should not be cause for concern.
Please let me know if you have any questions!"
 
It is good to know, not only are they aware of it, but they have a good explanation of the issue!
 
 
 

 

[Michgelsen]

Have you tried using the m9XX in USB class 1 mode? I've read instances where some computers have an issue with class 2 USB drivers causing static.

 
Yes, it doesn't make a difference. It's not a driver or software problem, it's an electrical problem. Something needs to be isolated which isn't at the moment. I tried applying a double layer of tape over pins 1 and 4 (which carry the power) of the audio-carrying usb plug, but it hasn't made a difference. Maybe the interference travels over the ground via the shell of the usb plug, or over the data lines. I could try cutting the usb cable and disconnecting the shield on one side, but that's not very reversible...
 
If you google this problem, which is kind of hard, because it's difficult to describe, you'll find a lot of people having similar problems with various usb audio interfaces. No real solution though.

 

[GraceDesign]

   
Yes, it doesn't make a difference. It's not a driver or software problem, it's an electrical problem. Something needs to be isolated which isn't at the moment. I tried applying a double layer of tape over pins 1 and 4 (which carry the power) of the audio-carrying usb plug, but it hasn't made a difference. Maybe the interference travels over the ground via the shell of the usb plug, or over the data lines. I could try cutting the usb cable and disconnecting the shield on one side, but that's not very reversible...
 
If you google this problem, which is kind of hard, because it's difficult to describe, you'll find a lot of people having similar problems with various usb audio interfaces. No real solution though.

Ground loops are always fun to figure out ;P
First, let's see if we can isolate where the loop may be. If you connect the m9xx to your computer only through the data connection (bus powered) and have nothing else connected but headphones to the m9xx, do you still hear the interference? 

 

[Michgelsen]

  Ground loops are always fun to figure out ;P
First, let's see if we can isolate where the loop may be. If you connect the m9xx to your computer only through the data connection (bus powered) and have nothing else connected but headphones to the m9xx, do you still hear the interference? 

 
Yes, I can still hear it. There's no difference between bus powered or adapter powered.
I can only listen with an external amp, because I'm using electrostatic headphones, and do not have electrodynamic headphones available to plug in directly to the m9xx.
 
Either way, this doesn't sound like a ground loop as I know it. I have my system grounded at one point only, so there should not be a differential anywhere.
It sounds like interference injected into the audio system by the motherboard, whenever there's cpu activity, such as selecting text. It's not constant, but influenced by what I do on the computer. My old laptop used to have this problem too on its integrated sound card. On the desktop system I use now, I hadn't heard it before. The problem isn't there with my m903. I can only think of two reasons: either its usb input is better isolated from the computer, or I never heard it because the interference was attenuated by its analog volume control. I did test it with the m903 the other day at full volume though, and couldn't hear it.
 
Any further assistance is most welcome. Let me repeat that the noises are very faint, and can only be heard when there's no music playing and it's quiet in the background. Still, I'd like the noises to go away.

 

[GraceDesign]

   
Yes, I can still hear it. There's no difference between bus powered or adapter powered.
I can only listen with an external amp, because I'm using electrostatic headphones, and do not have electrodynamic headphones available to plug in directly to the m9xx.
 
Either way, this doesn't sound like a ground loop as I know it. I have my system grounded at one point only, so there should not be a differential anywhere.
It sounds like interference injected into the audio system by the motherboard, whenever there's cpu activity, such as selecting text. It's not constant, but influenced by what I do on the computer. My old laptop used to have this problem too on its integrated sound card. On the desktop system I use now, I hadn't heard it before. The problem isn't there with my m903. I can only think of two reasons: either its usb input is better isolated from the computer, or I never heard it because the interference was attenuated by its analog volume control. I did test it with the m903 the other day at full volume though, and couldn't hear it.
 
Any further assistance is most welcome. Let me repeat that the noises are very faint, and can only be heard when there's no music playing and it's quiet in the background. Still, I'd like the noises to go away.

The m903's USB interface is ground isolated so the computer ground is not connected to audio ground. It sounds like it could be a ground loop with the computer ground and your amp ground. Have you tried a ground lift adapter on either the amp or on your computer? You could also try plugging the amp in to a different outlet to see if that helps.