stereolab42 said:

  Well, now I'm disappointed. The m920 DAC is shifting either the left or right channel 180 degrees out of phrase. That explains my problems with crossfeed killing the bass --cancellation. I'm using TrueRTA monitoring line-in on my computer as an oscope, and the freeware "Test Tone Generator" to generate tones. I've connected one of the m920 headphone outputs to line-in.
 
1. If sound output to the m920 goes through USB, 1.0 or 2.0, then the channels are out-of-phase.
 
2. If I send sound output through the unbalanced input in the m920, from line-out on my sound card, the channels are in-phase.
 
3. If I send sound output through the TOSLINK input in the m920, from TOSLINK out on my sound car, the channels are again out-of-phase.
 
I think this proves the DAC is at fault. I've tried playing with all sorts of m920 settings to see if something is affecting the phase, but no luck. Hopefully a firmware update can fix this.
 

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This is bad news. I was damned close to making a purchase. Let's hope Grace resolves the issue.

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stereolab42 said:

  Another problem: PCM playback over 192khz always stutters. Tried two different computers (Win7/Win8), multiple software stacks (JRiver/Foobar), multiple sources (DFF music tracks, tones). For example, a straight 50hz sine wave created in Audacity and saved to WAV at 384khz and played back through JRiver/Foobar will skip every few seconds. Bitstreamed DSD over DoP plays fine, but I need to convert to PCM to use DSP plugins (and of course fix the polarity on the left channel). Increasing all configurable buffering values in the playback software makes no difference, so I think the issue is in the m920 USB 2.0 driver (or perhaps the firmware).

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5/31--THE SPECULATION IN THIS POST ABOUT TECHNICAL PROBLEMS WITH THE M920 IS INCORRECT. PLEASE SEE POSTS BELOW.
 
It sounds as though this product was rushed to market to compete with the Mytek and Benchmark units. These are serious issues that ought to have been resolved before the product went to market. Very troubling . . . 

soundargument said:

   
This is bad news. I was damned close to making a purchase. Let's hope Grace resolves the issue.

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Nevermind looks like I misread.
 
*Editted*

stereolab42 said:

  Another problem: PCM playback over 192khz always stutters (via USB). Tried two different computers (Win7/Win8), multiple software stacks (JRiver/Foobar), multiple sources (DFF music tracks, tones), multiple output types (ASIO, WASAPI). For example, a straight 50hz sine wave created in Audacity and saved to WAV at 384khz and played back through JRiver/Foobar will skip every few seconds. Bitstreamed DSD over DoP plays fine, but I need to convert to PCM to use DSP plugins (and of course fix the polarity on the left channel). Increasing all configurable buffering values in the playback software makes no difference, so I think the issue is in the m920 USB 2.0 driver (or perhaps the firmware).

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Have you been in touch with the folks at Grace? Let us know how this all shakes out.

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stereolab42 said:

   
Yeah, I was emailing Alex last week with random technical questions, and then we were trying to figure out why I thought the xfeed was killing bass. I didn't discover the source of the problem (left channel polarity reversal by the DAC) until late Friday after they closed. Surely I will hear back on Tuesday (I will wait to ask about the >192khz issue until after this has been resolved).
 
I'm not really worried yet. I love the build quality, features, and SQ of the unit so I'm going to stick it out. I did a lot of research and concluded I wouldn't be happy with any alternatives close to the same price. I work in software so I know that brand-new products with a lot of new code are very likely to have some bugs that slipped through testing. They offer USB firmware updating so hopefully that's all that will be needed.

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Good to hear. The folks at Grace have an absolutely stellar reputation so I'm sure they will sort this out with you. I've owned a Grace m903 for 2 years now and it's been a rock solid performer. One of the reasons I got it was the 5 year transferrable warranty which speaks to a company that stands behind their products.

stereolab42 said:

   
Yeah, I was emailing Alex last week with random technical questions, and then we were trying to figure out why I thought the xfeed was killing bass. I didn't discover the source of the problem (left channel polarity reversal by the DAC) until late Friday after they closed. Surely I will hear back on Tuesday (I will wait to ask about the >192khz issue until after this has been resolved).
 

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Any word from Grace today?

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stereolab42 said:

  Latest update:
 
* Alex is fronting me a replacement m920. Yay! I have a careful set of tests lined-up as soon as I get the unit to rule in or out several scenarios. But hopefully it will work fine and demonstrate that there was just an early-run glitch with the other unit.
 
* I bought an Oppo HA-1 as a backup amp. They offer local pickup at their headquarters so I couldn't resist. The amp has no issues with polarity or 32/384 PCM so that makes it far less likely that the m920 problems were with my setup (although anything is possible... some trinary interaction between a piece of malware, the Grace USB driver, and their firmware? Who knows? I solve software problems for a living so I'm actually having fun now.)
 
* The Oppo is excellent but the m920 (in its theoretical 100% working form, at least) still conclusively beats it in my book, justifying the price delta. I will give a more detailed comparison once these issues are ironed out. SQ is outrageous on both, however. In this day and age, at this price range, SQ is NOT an issue. It's features.
 
* Yes, I'm a spoiled brat.

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That's great to hear that they're working hard to resolve your issue.  Please keep us posted!

After reading Stereolab's experiences, I would like to chime in, as a very happy m903 owner, and say that the tech support and service of Grace Design is superb. I had a problem with my unit a long time ago, ultimately caused by faulty fuses I got locally for converting the m903 for 230V operation, and Alex was very quick to help and make arrangements for repair with the local distributor.
 
I must say I'm tempted by the new m920, although I'm wondering whether or not the upgrade from the m903 would be incremental at best. I'm using the m903 as a dac/preamp only, with an external (electrostatic) amp, so the internal amp and crossfeed are of no concern to me. Furthermore, does anyone here really have that many DSD recordings or 32/384 material to justify an upgrade..? I think not. Thus, the question is how much of the improvements are to the d/a conversion of 16/44 material and/or the analog stages. Opinions on these matters are most welcome and IMO more relevant than 'omg it does dsd' and the like.
At least the m920 looks better overall, and we all know better looking equipment sounds better.

michgelsen said:

  After reading Stereolab's experiences, I would like to chime in, as a very happy m903 owner, and say that the tech support and service of Grace Design is superb. I had a problem with my unit a long time ago, ultimately caused by faulty fuses I got locally for converting the m903 for 230V operation, and Alex was very quick to help and make arrangements for repair with the local distributor.
 
I must say I'm tempted by the new m920, although I'm wondering whether or not the upgrade from the m903 would be incremental at best. I'm using the m903 as a dac/preamp only, with an external (electrostatic) amp, so the internal amp and crossfeed are of no concern to me. Furthermore, does anyone here really have that many DSD recordings or 32/384 material to justify an upgrade..? I think not. Thus, the question is how much of the improvements are to the d/a conversion of 16/44 material and/or the analog stages. Opinions on these matters are most welcome and IMO more relevant than 'omg it does dsd' and the like.
At least the m920 looks better overall, and we all know better looking equipment sounds better.

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That's always the question isn't it? I do know that moving from the m902 to the m903 was well worth the cost in my case. Guess I'll wait for further feedback on the m920.

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* The Oppo is excellent but the m920 (in its theoretical 100% working form, at least) still conclusively beats it in my book, justifying the price delta. I will give a more detailed comparison once these issues are ironed out. SQ is outrageous on both, however. In this day and age, at this price range, SQ is NOT an issue. It's features.

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I would appreciate further explanation regarding the differences between the Oppo and the m920. Your post seems to suggest that the sound quality of the two units is equal, but that the m920 is worth the difference because of more features. Is it your view that sound quality is roughly equal? What features of the m920 give it a "conclusive" edge?