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Grace Design m903 Async USB To 192k

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There are two analog line outputs, called L1 and L2.


L1 is the balanced line and this uses the TRS connector. You can use a TRS to RCA cable, no issues..repeat, no issues.


L2 is the unbalanced output, using RCA connectors, there's only one unbalanced audio line out RCA connector.


You can adjust L1 and L2 together, like a true ganged setup, so both will have the same output level.




you can adjust either L1 or L2's level individually to match gains to different pieces of equipment. I would imagine using this in a bi-amp setup for room equalisation or similar or if you have two amps from different manufacturers.


All this is in the analog domain.


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  • 3 weeks later...

Thought to share some experiences with the m903 to answer some posters questions at the same time.


As packaged, the m903 is wrapped in a bubble with compressed air, which protects it admirably in transit. The DAC is supplied with a quick start quid, a printed manual, USB A to USB mini cable about 6’, and a power cable terminated with an IEC320.


The DAC I received had what looks like oil stains or rub marks, as if when the hole was made, the swarf marks from the metal scratched the surface and left a clear imprint. The front panel is 316 stainless with matching aluminium knobs. The whole DAC seemed to be covered in a very thin film of oil, maybe the compressed air that blew up the bag to pack the DAC had an air filter that needs cleaning…? So every time you touched the black surfaces on the DAC, you could clearly see fingerprints, the oil came off with a microfiber cloth easy enough, a user should not have to do this, after all, this DAC may not end up in a recording studio but someone’s home. The finish on the case would certainly not pass rigorous Japanese quality systems, but the USA, it’s about the norm.


The m903 runs about 10C above ambient temperature, so it’s hot to touch or a great heater.


In use

To set the ANALOG volume control is to either use it as a standard volume control, or you can pre-set the volume to match your pre-amp. You can switch off the line level outputs either TRS balanced or RCA unbalanced or both, and just use the dual Headphone outputs if you wish, the m903 is very flexible in that regard. The TRS connectors aren’t that common in audiophile terms, but to their credit, TRS is a pro standard for many years, and the reliablity of the connector can’t be disputed. I bought a pair of Volox cables TRS to Female XLR to start with, fed into the E-450 amp Line balanced input.

The menus for the DAC are easy to use, if you can use an ipod, microwave oven with a rotary selector, you can use the m903’s selector with ease.



The m903 uses a mini B connector, for this DAC I bought a 6’ Wireworld Starlight, principally to make sure that the cable doesn’t influence the Class 2 Audio transmissions. U1 mode is your classic USB selection up to 24/96. U2 mode is USB Class 2 audio and with a MAC can transmit 24/192 with OSX standard (for now anyway) and under Windows a Theyscon driver (more on this later).

Other inputs are AES (no output from PC, so didn’t use), SPDIF to 24/192 and Toslink Optical to 24/96. I stuck with the USB input to playback 176/192 files with minimal of hassle on a MBP.


With Pure Music under the “right” conditions, PM is a charm with this DAC. U1 mode is not that great, with a lot of loss of detail, but U2 mode, the resolution really shines, it’s quite a difference, lot more detail and accuracy. On some occasions, when switching tracks I would get white noise, but not all the time.



For me, this didn’t work, a lot of silence at times. Plays for a bit, then drops off to silence.



This player needs some a lot of work to be reliable, although the DAC behaviour is not directly responsible for this, the auto sample rate switching detection fails to work, when you exit Fidelia, or it crashes and burns in a trail of white noise. Quite often you have to reset audio Midi, and this is where the m903 stumbles a bit. Often this player would be fine, then no sound or progress. From other posts it looks like a network feed issue from a NAS.


M903 as a headphone amplifier

Yes, it works very well into the Denon AHD-7000, I can detect no difference on the sound when I compare to the Accuphase E-450’s headphone outputs, same solid drive, great bass, beautiful detail.


OSX and m903

You can have a favourite player, doesn’t matter which one, if you select a sample rate, from say 44.1 to 96 you get a very audible click, these can vary from (a guess from Sound forge pro’s scaling is -20db) to a nasty peak of -6db. If you add this figure directly to your power amp’s gain, just be prepared for tweeter rotors to fly past your ear.

This word of caution from the m903 manual states : “The m903’s headphone outputs are protected from any popping when the unit is turned on or off. However, if you are using the line outputs, observing proper power sequencing is recommended to avoid any potential popping in your speakers. Before powering up your m903, make sure your monitor speakers or power amps connected to your monitors are turned OFF. Once the m903 and the rest of your audio system are powered up, then turn on the power to your speakers or amplifiers. When powering down, first power OFF your speaker system and / or power amps and then power down the m903. Turn power amps on last, turn them off first!”


I made the mistake of powering up my integrated first, then the m903 and the above sentence is confirmed. Well, if you wish to use the m903 directly to a power amp, I would recommend NOT doing this, first you can make an error in the power up sequence and also when the sampling rate changes and experience tweeter malfunction.


I did refer this problem to Grace Design and they were helpful in trouble shooting this problem, however, the muting of when the sampling rate was changed under OSX was out of their control, and their hands are washed from this matter. Muting is a breeze for other DACs if there is a loss of sync or the SR changes , I don’t see why Grace Design doesn’t follow, and tweeters are not cheap!


See also this thread.



During the troubleshooting phase, I used the Halide bridge into the SPDIF input on the m903, the chirp noise when changing the SR, changed to a high pitched squawk instead.


Win7 and m903

I thought to try the m903 with Foobar2000 using the Thesycon driver for >24/96 files to circumvent the SR switching problem to see how Windows would behave. The drivers installed without issue, and I set the m903 to u2 mode. Test track I used was from MFSL Fragile Album, “Mood for a Day”, a lovely 6 string acoustic guitar piece with slight echo. You get to hear the slide of fingers on the strings, and a resonance and decay of the strings, so it’s a good test. Well first off there was a stutter playback under WASAPI when playing form a NAS, however this disappeared from playing from the local SSD drive. Google to the rescue and invoke this spell from the administrator’s command line “netsh int ip set global taskoffload=disabled” and this worked well. Changed the buffer in Foobar to 150ms from 50ms for the Halide and no more stuttering.

As for the music, the m903 under windows 7, the switching noise when you change a song from a 16/44 to a 24/192 on the fly is GONE, so that’s a *big* plus and put a smile back on my face. As for the music, well my 54yo ears find Windows trumps OSX by quite a bit, especially on “Mood for a day”, you hear everything, the lovely resonance and decay of the strings, movement of fingers and hands, OSX with PM is nowhere near this level of detail, let any other player on OSX, sounds classically veiled in comparison. I did try my regular DAC-20 and the results are the same.


After about six months of using the i5 MBP, it’s now de-commissioned as a music server in favour of a Sony Vaio and Foobar2000. That also concludes and finalises the debate on the two OSs as far as I am concerned.


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Many thanks to one and a half for his feedbback.

Very interesting advice concerning the Trs to Xlr cable. I thought that I couldn't use the balanced input of my amp with the M903...

Using a Nas with a XP audio PC, I don't have any issue on stutter playback but will certainly use suggested adjustments when I will change to Win7.

Being a Pc+Foobar user and looking for a quality playback Dac+headphone for my "late" office work, the M903 seems the way to go.


Chris, sorry for stuttering, but your review is much expected.



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The cables offered by the dealer are Vovox sonorus direct S types, more info here:




The m903 for late night with headphones would be a great application, I use the m903 in this application frequently. To each their own with the sound, the headfi lot could pick differences for headphone amps, but the differences were so, so small between a 200W/ch near short circuit capable amp and the m903, I could listen to either one and couldn't tell. Either one is great!


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Nope. If you have to feed it into an integrated you'll have to struggle with 2 volume controls and decide what you wanna do with each.


Source: Foobar2000, NAD C565BEE, OPPO 83; DAC/Amp: Grace Design m903, NAD C375BEE; IEM: Westone 4; Headphone: markl Mod MD5000; Speakers: Dynaudio Acoustics BM5A MKII, PSB Imagine T

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Here are your choices.


The m903 uses a Cirrus Logic volume control IC at the analog level. Short of removing the chip and re-engineer the backend, this chip can't be defeated with say a bypass switch.

You can, however, pre-set the m903 balanced or unbalanced outputs to a gain of 1, the balanced output has a maximum of +27dbu, unbalanced +21dbu, so there's enough headroom for anything.


I have mine set to a preset value of 88 on the dial, which works out to the same gain as a Halide Bridge. As the m903 boots up, this level is always maintained as a choice you can make. I then use the amp's volume control in analog, rather than mess with the computer's player volume control, a topic of a lot of discussion on its own.


The Concentra has a volume level display, so with a steady test tone, you can set the gain of the m903 to match 0db, and keep this permanent. The output distortion is so low from the m903 with the Cirrus chip, it looks like it has better characteristics than a humble pot as far as distortion goes. I would also say balance with the chip would be far superior, although you can set this as well with m903.



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Am I correct in thinking that I can run analog RCA pair out from SACD player directly into the m903's unbalanced RCA analog inputs?


MacMini (late 2010 w/ 4 gb @ 10.9.5) dedicated to digital music (hi-res @24/96 FLAC & lossless @16/44.1) via Audirvana+ 1.5.12 * thru AQ Carbon USB to MF V-Link 192 to MF M1 DAC via Mogami Gold AES (XLR) * out to Sennheiser HD800 driven by Burson Audio HA-160 OR (when wife not home!) out to Paradigm Studio 60s driven by Golden Tree Audio SE-40 tube stereo amp * MacBook (lossey @iPod/iPad/iPhone/AppleTV + general computing) * MacBook Pro (late 2011) @ripping/tagging DVD-Audio + Blu ray Audio & for travel via Fiio E-17 * iPhone5 64gb w/ FLAC player

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Yes and it will function as a headphone amp or volume control via it's balanced/unbalanced outs.


Source: Foobar2000, NAD C565BEE, OPPO 83; DAC/Amp: Grace Design m903, NAD C375BEE; IEM: Westone 4; Headphone: markl Mod MD5000; Speakers: Dynaudio Acoustics BM5A MKII, PSB Imagine T

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I'm thinking about buying the Grace, though I was hoping to see a review from Chris first. I like the fact that it has an analogue input that bypasses the DAC and has Rankin's async, as well. I'm not a techie, so wanted to ask if someone could answer a question or two.


First, I plan to try it with and without a preamp. I'd like to understand if I can use it as normal preamp with a quiet volume control (unlike, say the Benchmark)?


If so, can I also put a phono pre in front of the Grace analogue input for my TT?


I'm thinking I'd like to connect my Squeezebox to it also. Is it possible to do this?


Finally, I'm wondering if I can connect my CD player to it? As I write this, I'm imagining that maybe I should just be buying a simpler DAC and stay with a conventional pre so I can hook everything up to the pre. I've been waiting for the Classe CP-800 to come out, but it is quite delayed.








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I am aware that upsampling is a controversial topic, but I wonder if anyone knows why Grace chose not to use an upsampling filter? I have an upsampling (16/192) CD player, and I have enjoyed it for some time. Not being able to audition the Grace, I'm curious about this issue.


I know it has nothing to do with upsampling, but I've read about Ayre's MP filter and did hear the QB9 in my system. I loved it but hoped to find something with similar sound and more features. Has anyone compared the Grace to the Ayre?


Thanks for the earlier answers to the questions about the Grace as a preamp.



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Yes, I did compare these two on a pair of Genelec 8040 active speakers for a period of two weeks. I had a well-burned-in qb-9 connected to the balanced ins of the brand-new m903, which thus served as a preamp throughout my listening sessions. In addition to those active speakers, I compared the two also via Beyerdynamic headphones using the headphone amplifier of the m903.


In fact, I was hoping that the m903 would match the sound quality of the qb-9 but with that one feature I was really missing in the qb-9: an excellent analog volume control. (The headphone amp and the possibility to use a remote control with the m903 I considered to be additional bonuses. I was not looking for those in the beginning. In fact, with an analog volume control in the qb-9, I think I would have bought it already two years ago.)


I compared the qb-9 and the m903 (using USB2 mode) with a wide range of music: symphony orchestra, classical music, opera, jazz, audiophile music, heavy metal ... Here is the summary of my (!!!) personal impressions: Soundstage was equally excellent with both units. In total, the qb-9 sounded more organic and more relaxed when setting the digital filter to "Listen". Also bass and voices had more substance and weight. However, there were also tracks where the m903 did outperform the qb-9. The m903 had more extension towards higher frequencies and was somehow faster than the qb-9 (i.e., separate notes in fast violin solos or guitar solos vs. "overlaping notes"). Also the bass with the m903 was sometimes more accurate (e.g. when listening to Yello). That was an interesting experience as it showed me some deficiencies of the qb-9. However, somehow the m903 did stress me to some extend every time when I was listening to it. (Note: When using the qb-9 in "Measure" mode it also had more extension towards higher frequencies but then I also found the qb-9 to stress me to some extend.) That was a subtle effect. (Not sure whether that m903 unit had maybe not enough time to burn in.) Moreover, I really found voices (and especially female ones) too thin and was really missing bass. While those shortcomings were not so pronounced when listening via headphones, they were the reasons for returning the m903 ... although it was a hard decision at that point (i.e. prior to exposure to the LIO-8).


I was trying really hard to get also the Metric Halo LIO-8 to my place for further direct comparisons. Although making phone calls almost every day for about two week to some local music store, that did not work out here in Germany. (At some point, I received a LIO-8 , which however was broken and did not play a single note. That really drove me crazy but is another story.)


Some months have passed. By now, I finally pulled the trigger and bought the LIO-8 (after three weeks of testing on a pair of Genelec 8050 active speakers) and I am very, very happy with it. It sounds so natural, has an Apple-remote-controllable analog volume control on board, wider frequency extension than the qb-9, excellent bass and timing (no overlapping notes in fast solos), headphone amp, multi-channel and thereby surround capabilities, etc. Despite its remarkable extension towards higher frequencies, the LIO-8 does not stress me while the m903 did. Although I did not have the chance for a direct comparison, here is what I recall from my memory of the qb-9: Maybe (???) the qb-9 sounds more relaxed and a bit more organic than the LIO-8 (with maybe even a little bit more detail but not sure about this) but I am not sure whether this is not some sort of coloration ... however, in addition to its coloration-less nature, the significantly enhanced versatility of the LIO-8 convinced me to pull the trigger.


I am looking forward to Chis review of the m903 and his opinion on how it compares to the qb-9.


BTW, thanks to Chris, this forum, and its participants (Claudius, Barry, ...) which made me aware of the LIO-8 in the first place. It's a great page for computer audiophiles!!!!!!


Apple Powerbook G4 15\", iTunes, Metric Halo LIO-8, active speakers

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I purchased the m903 about six weeks ago, intending it to replace the m902, which has functioned as my desktop monitor and DAC for approximately five years.


I use the m902's DAC via toslink from an iMac and its line stage to drive Dynaudio BM6A's via TRS balanced outs. Headphones are Sennheiser HD650's and HD800's.


I work a lot with 24/96 and more recently 24/192 files. The m902 does 24/192 but not from the iMac (w/o adapters) since neither firewire nor asynchronous USB is supported by the m902. Prior to switching to Mac, I used the m902 with a XP machine and a Lynx 22 card. 24/192 performance was excellent via AES and I preferred the m902 DAC to the DAC on the Lynx 22.


The m903 adds asynchronous USB, improved DAC's, analog output stages and volume control, both single ended (RCA) and balanced outs (vs. the customer's choice with m902), while maintaining single ended (RCA) and balanced inputs.


As a DAC, I think the improvement in sound quality of the m903 vs. the m902 is dramatic, likely primarily due to the asynchronous USB technology. I can't imagine better ergonomics, especially with regards to managing and customizing the three outputs relative to each other (more on that later).


I have been personally surprised that I have come to prefer asynchronous USB to firewire; I feel it has a bit of a "relaxed" sonic signature with both the m903 and Ayre QB9.


Most recently the Weiss DAC202 has been the hub of my primary computer based stereo system (Mac Mini-DAC-DNA Sonett Headphone amp and to Bel Canto Ref 500 to Audio Physic 25th Anniversary Virgos, Cardas Golden Reference interconnects, custom speaker cables and power cords from Cardas wire). During the past 18 months, I've also owned an Ayre QB9, a Bel Canto 3.5 and a Benchmark DAC1 HDR. All were in the house at the same time. I chose the Weiss over the QB9 simply because I wanted to dump the pre amp for the first time in over 40 years.


Well, I recently sold the Weiss DAC202 and replaced it with the m903, and I'll be purchasing a second m903 to replace the m902 in my desktop system, as originally intended. This decision really had very little to with price. The m903 easily holds its own against all of the aforementioned DAC's, has superior ergonomics, and the additional benefit of a couple of analog inputs. I’ve been working at archiving close to 2,000 LP’s at 24/92 and 24/192 since 2002. The balanced inputs enable me to monitor the Busman Audio modded Korg MR1000 without cans, a convenience sorely missed since I dumped the BAT 52SE.


I believe that DAC’s at this level come down to personal taste, how they synergize with the rest of our gear and, nowadays, software. For me, the m903 via the USB 2 setting (with Cardas USB cable) really shines with Pure Music, Fixed Integer Mode for files of 24/92 or higher resolution.


The m903 is also an excellent headphone amp, though I do most my of critical listening to the HD800's with a DNA Sonett via the SE outs of the m903 (previously, the SE outs of the DAC202) or attached directly to an Ayre phono stage.


The m903 is certainly capable of driving the HD800's, and both it and the m902 excel with HD650's. To my tastes the relaxed character of asynchronous USB mates well with the HD800’s, as do the tubes in the DNA Sonett. I really enjoy the crossfeed feature with the HD650's but leave it off with the HD800's.


I doubt the head-fi.org crowd would consider the m903 or m902 reference headphone amps and I suppose I'd have to agree with them when comparing it to something like an Apex Peak. However, imo, it is significantly superior to the headphone amp in the $7,700 Weiss DAC202 and certainly as good as the current Benchmark DAC 1. The main reason I bought the DNA Sonett was that I was disappointed in the headphone amp in the Weiss DAC202. With the m903, I think I could live without the DNA.


Back to ergonomics for a minute; with the m903 it's so efficient and easy to control the line outputs independently or ganged together, or mute non-selected outputs. Additionally, each output level can be adjusted +/- 9.5 dB in .5 dB increments. This is extremely useful to me in mating the m903 with the DNA Sonnet with the optimum output level. Finally, each output can be set to a default volume level upon power up. These features would work superbly for anyone wanting a pair of active sub-woofers in their system.


Contrast to the Weiss DAC202, where I was forced to turn the power amplifier off to listen to the DNA Sonett exclusively. I also enjoy being able to adjust balance on certain recordings, having a mono option and having volume controlled in the analog domain.


I've owned several Grace Design products over the past ten years. Build quality is rock solid and customer service is unrivaled.


I've been a hi-fi and pro audio hobbyist for 45 years, and have been working with computer music servers since 2002. The m903 is the best two channel audio value I have ever encountered.



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