Selection Guide

Boulder Colorado's Grace Design launched their model m901 headphone amplifier in 2000. 5 years later came the m902 which set new standards for the category of compact reference playback high-end audio tools. Now arrives the m903 expressly engineered to be amongst the most refined and feature-rich headphone amp, DAC and monitor controllers available in the industry. The m903 keeps everything that was cool about its predecessors, adds useful new features and delivers even better audio performance. A newly designed volume potentiometer offers higher headroom (!) and significantly lower noise distortion specs. New-generation Grace DAC topology and a nifty ultra-low noise balanced-current-to-voltage converter yields even more precise musical resolution versus the m902. New 'S-Lock' PLL circuitry further lowers any phase noise and jitter plus the vastly improved power supply design galvanically isolates headphone amplifiers, line amplifiers, DAC's and the digital logic, again resulting in lower measurable noise and distortion. The re-designed m903 high-speed USB interface contains proprietary Grace technology with a completely asynchronous data transfer mode, which allows for bit-perfect USB playback with zero interface-induced jitter. This design affords standard driverless USB Class 1 use with Windows & Mac up to 24-bit/96kHz and USB Class 2 audio for 24-bit/192kHz operation on Windows & Mac (updated audio drivers required for 192kHz Windows operation). To us, it's clear that what the Grace Design m903 really delivers for audiophiles is upscale computer-based reference playback, lovingly perfected.

Grace Design's crossfeed circuitry has a gentle compensation to eliminate the perceived waver of low frequency content. Both balanced and unbalanced line outputs are now standard -- yay! -- with individual volume controls for each. Provided is a 'mono' mode ideal for checking a recording mix for phase issues or simply monitoring the production in true monophonic sound. In our opinion, these Grace Design improvements cement the m903 as the perfect compact reference monitor controller, especially for commercial production environments employing more than one set of monitors. A full complement of analog and digital inputs are aboard (balanced, unbalanced, AES3, S/PDIF, TOSLINK and USB), all easily selectable via a precision-machined rotary switch located right on the front panel.

Grace also offers an updated [optional; sold separately] infrared remote control, which provides essential convenience for anyone working out of easy reach of their m903.

Features

• Balanced and unbalanced analog inputs
• 24bit/192kHz digital stereo inputs- AES3, S/PDIF, TOSLINK and USB
• High speed USB interface – completely asynchronous transfer mode allows for bit-perfect playback with zero interface induced jitter
• Driverless operation on Windows & Mac up to 96kHz/24bit
• Supports USB Class 2 audio specification for 192kHz/24bit operation on Windows & Mac (drivers needed for 192kHz operation under Windows)
• New generation DAC’s and ultra low noise balanced current to voltage converter yields more musical performance compared to the m902
• Mono mode for checking mix phase issues (or listening to Pet Sounds)
• s-Lock™ phase lock loop sample clock regeneration for ultra-low jitter and rock solid digital stability
• High-current transimpedance headphone amplifier circuitry built to effortlessly drive low impedance headphones
• Balanced and unbalanced variable level analog line outputs
• Improved power supply architecture isolates headphone power amplifiers, line amplifiers, DAC’s and digital logic
• Precision level control with a 99.5dB range in 0.5 dB steps
• Channel level matching accuracy of 0.05dB
• Improved x-feed circuit eliminates perceived loss of low frequency content
• Optional infrared remote control available
• Internal linear power supply with custom wound toroidal transformer
• Sealed gold contact relays used for all signal switching
• Five year transferable warranty on parts and labor

wonderful clarity and depth
Posted by wellaged from my easychair on 2011-03-03

Recommend Product: Yes
Pros: texture-detail and soundstage
Cons: runs a little hot

I am a headphone fanatic. throughout my lifelong attraction to great sound I have been fortunate to have owned some fantastic audio equipment. My wife has been tolerant of a living room that more closely resembled a sound studio. But I always turned to my headphones when I really wanted to immerse myself into my music. I currently listen to sennheiser HD 800's through my Grace 903. The detail and the texture of the sound I am experiencing is spectacular. I did have the headroom ultra desktop amp (with the senn hd 800) and the Grace 903 is far more detailed with a deep and lush soundstage the ultra just could not match. I sense placement in my classical music that I have never heard before.... tonally balanced with little coloration. My ulta desktop was slightly veiled in comparison. If the recording is good this rig will deliver an experience well worth the investment.

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How do they Cram all of that Slam?
Posted by NA Blur from Bozeman, MT on 2011-02-18

Recommend Product: Yes
Pros: Compact, Versatile, Great Sounding, Fun
Cons: No over emphasized bass, runs a bit hot

Grace m903 + Denon AH-D2000 = An amazing synergy!

Value:

For $1795 US you receive quite a package. You get a headphone amp, a speaker pre-amp, and DAC. The connectors are quite fantastic making the m903 one of the more favorable mid-range audio devices due to sheer versatility.

Soundstage:
The soundstage presented by the m903 is awesome. The mids and highs on the m903 are swift, immediate, and enjoyable. The soundstage can go from left/right, up/down, and the many combinations with ease. The audio presentation was anything but one dimensional.
Tested: Buddy Miller & Julie Miller - [Written In Chalk CD1 #05] Long Time

Bass Impact:
I initially felt that the m903 was a bit weak on the bass end. Not true. The sonic signature depends on your headphones. I paired some Denon AH-D2000's with the m903 and have basically sold everything I had because the combo sounded so amazing.
Tested: Sean Jones - [Kaleidoscope CD1 #05] So Wonderful

Bass:
The bass is somewhat lacking initially. After a few days of analytical listening I realized that the bass will go just about as deep as you want it to. I used some subwoofer test tracks with my AH-D2000's through the m903 and it definitely went deep. Remember that the m903 is pure and true so you need a great track with pure bass in it to hear what it can really do.
Tested: Karsh Kale - [Realize #03] Tour Guide

Mids:
No questions here the mids were strong. The mids were beautiful and articulate.
Tested: Ella Fitzgerald - [Verve Unmixed CD1 #07] Wait Till You See Her

Highs:
Another easy test for the m903. Even with my HD-650's I could here detailed and very quick highs. No problems with the highs that I could hear.
Tested: Michael Jackson - [The Essential Michael Jackson CD1 #16] Billie Jean (Single Version)

Quality and Design:
The unit itself is not too heavy nor too light. It comes with well thought out exterior design and button layout. The back panel is well constructed and the source selector is bomber. One gripe I had here was the feel of the volume control. It wiggles up and down easily. I would love to see / feel the Music Hall 25.2 volume knob on this bad boy. The knob grips are a bit weak as well. I found no major Quality Control issues and the 5 year warranty is simply awesome. The box it came in was very nice and there is a plastic pressure sleeve in the box to minimize shipping damage. The feet that come with the unit can be tightened down too far and they will dig into the bottom of the chassis. I had to use some felt, an o-ring would also work, to keep the two metal surfaces from touching. This also allows the unit to be better balanced on all fours. Some have complained on the m902 that it will not rest level. The m902 has the same issue until I used you use some felt and are able to control the tightness of each setscrew.

Overall:
After months of testing and intense listening the Grace m903 is an amazing piece of equipment. Perhaps not quite as airy or bassy as the Ultra Desktop, but it certainly delivers in clarity and soundstage. Paired with some AH-D2000's and DT990's ( 250 Ohm ) the Grace m903 is pure bliss. I did test some LCD-2's through the m903 and they sound awesome as well. I just prefer a lighter can.


Deciding Factors:
If you want an articulate and great sounding device with DAC and you do not mind sacrificing 5-10% of your bass range ( keep in mind you gain the mid/highs ) as well as a device that has many inputs / outputs then the m903 is for you. Like I mentioned before I paired mine with some AH-D2000's and honestly cannot listen to anything else even at higher price points. If you prefer extreme bass and an even smaller footprint the Ultra Desktop will be fore you. The more I listen to the m903 the more I appreciate what it is and how it sounds.

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