- Jun 20, 2001
Written by Jude Mansilla
Ever since I laid eyes on the Grace Design m902 DAC and headphone amplifier combo ten years ago, I wanted to own something made by Grace. The Grace m902 was a stunning piece of gear to look at, at a time when headphone-driving gear was not often, well...sexy. There was much more to the m902 that captivated me beyond its looks, though. The m902 was released at a time when DAC/amp combo pieces weren't nearly as common as they are today, and was among the first high-res USB DACs that also had serious design focus on the headphone amplifier circuitry. In a sure sign of how serious they were about its headphone output performance, Grace Design even licensed Jan Meier's crossfeed design for the m902, and I was (and still very much am) a fan of crossfeed when it's needed.
(Above) Grace m902, which has long since been discontinued.
Somehow, I never ended up buying the m902. The years passed, the m902 was discontinued, replaced by the m903 (which had a new crossfeed circuit by Grace designed to minimize perceived bass loss). Last year, the m903 was replaced by the improved (and still current) m920. Over the years, though, several visits to recording studios equipped with Grace gear kept Grace Design on my mind.
Then, some time ago, Will Bright from Massdrop called me to ask if I was familiar with Grace Design. Not only was I familiar with Grace, I said, but proceeded to tell him all of what I just told you in the paragraphs above. He told me Massdrop was working on a collaboration with Grace to take all of the audiophile components in the nearly $2000 Grace m920, to improve them where possible, and then to release it as something more accessible, more affordable. Assuming all went as planned, they were shooting for around $500. I sent him my credit card info. (If you think I'm joking, you can ask him yourself.)
Months had passed, a plain box arrived, and inside was this:
It's called the Grace Design x Massdrop m9XX DAC/Amp. "Let me know what you think," Will said via text. "Take my money," I replied--and I hadn't even heard it yet. Well I've heard it and used it now, and I'm happy to report that Grace Design and Massdrop have crammed a lot of performance into this little beast. Go ahead and charge the card, Will.
Whereas the $1995 Grace m920 uses an ESS Sabre DAC, the Grade x Massdrop m9XX employs AKM's flagship AK4490 DAC. It is 32-bit 384kHz capable from USB (and 24-bit 96kHz capable from optical). The m9XX's also supports DSD up to DSD128 via USB.
The power supply of the m9XX is a very cool adaptive design that allows for some nice flexibility, with both low-power and high-power modes. In low-power mode, the m9XX can be powered strictly from USB buss power, outputting up to 100 mW per channel into 32Ω. If you also use the second USB power input on the m9XX, however, high-power mode is enabled and increases the m9XX's performance, including increasing maximum output at 32Ω to a robust 1020 mW per channel. (Grace x Massdrop includes a 5V, 2A power supply with the m9XX.)
Inside the m9XX, five separate power supplies are designed to deliver clean, isolated power to the digital and headphone amplification sections. Of this power supply, Grace x Massdrop said this: "The power supply...is carefully filtered with multi-tiered noise suppression for artifact-free playback from the sensitive DAC circuits and amplification unrestricted by any annoying buzz or background hiss." My first impressions suggest this is a very fair claim (which I'll comment on later).
Michael Grace also added: "As for AKM implementation in this box we worked hard on power supply filtering. USB buss noise can easily pollute clock timing and DAC reference voltages. AKM DAC is much more immune to power supply noise than Sabre. Sabre requires elaborate and expensive power supplies to work correctly. Also, we were able to get actual dac harmonic distortion lower than AKM specs with our analog filter design."
Speaking of filters, the m9XX offers user-selectable digital filter settings:
- F1: Sharp roll off, linear phase;
- F2: Slow roll off, linear phase;
- F3: Sharp roll off, minimum phase;
- F4: Slow roll off, minimum phase.
The m9XX's headphone section incorporates Grace Design's latest crossfeed, identical to the crossfeed circuit used in their $1995 m920 DAC/amp. Again, I am a big fan of crossfeed, when it's needed. With exaggerated stereo recordings (like a lot of stereo Beatles) containing unnatural, extreme left-right panning, crossfeed (for me) can be an absolute must.
I also want to point out that the m9XX's headphone amp's output impedance is a super-low 0.08 ohms, so you should have zero issues where that's concerned.
The Grace Design x Massdrop m9XX arrived at a time when my travel schedule was (and still is) going full-tilt. Since the m9XX weighs only 14 ounces and measures a very compact 4” x 5.25” x 1.8”, it has been accompanying me on my travels. I'm in Tokyo now for the Tokyo Headphone Festival, and I was informed that Massdrop is announcing the drop for the m9XX today, so I wanted to give a few quick impressions of the m9XX:
- I will confirm that the m9XX is dead quiet with most of my headphones. Plugging in my very sensitive FitEar MH334 custom IEMs--which usually dive well into the noise floor of headphone amps--reveals almost perfectly dead silence from the m9XX, which is impressive.
(Above) FitEar MH334 Customs with Grace Design x Massdrop m9XX
- I did some quick preliminary measurements of the m9XX with the Audio Precision APx555 audio analyzer we have at the office, and the SNR (signal to noise ratio) of the m9XX measured an impressive 110+ dB. The m9XX's frequency response from 20Hz to 20kHz was also impressive, deviating no more than 0.08 dB in either channel across that range. (I'll share more measurements of the m9XX after a more careful measurement session with it.)
(Above) Preliminary measurements of Grace Design x Massdrop m9XX using Audio Precision APx555 audio analyzer. Signal to noise ratio (left) and frequency response deviation (from 20Hz to 20kHz).
- The sound when driving my MH334 custom IEMs is superb. In addition to the very low self-noise, I love how the m9XX doesn't comes off as clinical or dry, despite its resolving nature.
- I find many (perhaps most) desktop amps have overly aggressive taper with the ultra-sensitive FitEars, which is most certainly not the case with the m9XX. The m9XX's volume control allows very fine, very precise control with the FitEars.
- I tried the Astell & Kern AK T8iE (a lovely smooth sounding, high-end universal-fit IEM) with the m9XX, to see if the smooth-yet-detailed quality of the m9XX would come off as overly mellow with the AK T8iE, and was thrilled to find that wasn't the case at all. The AK T8iE maintained its character, but detail still jumps very nicely from them from the m9XX. (The m9XX, in terms of self-noise, is also dead silent with the AK T8iE.)
(Above) Grace Design x Massdrop m9XX with Astell&Kern (and beyerdynamic) AK T8iE.
- The m9XX has paired well with the Audeze LCD-4, driving it without any sense that I was shortchanging the new $4000 Audeze flagship. Midrange resolution and body--LCD-4 strengths, to say the least--were served beautifully by the m9XX. Power on tap seemed more than up to the task with the LCD-4 in early listening. I'll do more listening with the LCD-4 and the HiFiMAN HE-1000 (the latter of which I haven't plugged into the m9XX yet) when I settle back in at the office.
- I've only preliminarily used the Sennheiser HD 800 with the m9XX, and it is a very nice and surprising pairing. I only mean it's surprising to me in that I haven't found many small form factor solid state amps that I'll use with the HD 800. Add one more to the list. Will it replace my favorite tube amps with the big Sennheiser? No. But for a rather portable monitoring setup...wow. I'll have to spend more time with this combo.
(Above) FitEar MH334 Custom and Sennheiser HD800 with Grace Design x Massdrop m9XX.
- I have also preliminarily used the new Shure KSE1500 electrostatic in-ear system fed by the Grace Design x Massdrop m9XX, and here's what I'll say, at least as far as first impressions go: If you pick up the KSE1500 and its $3000 price tag has your budget nearly tapped, yet you need a worthy source for the flagship Shure...seriously consider the m9XX.
- The build quality of the m9XX is wonderful. Its gorgeous chassis (co-designed by Massdrop's Will Bright) is made of aluminum and steel, and has a beautifully contoured, thick top plate that gracefully cascades over the front and rear of the m9XX. As someone who's always wanted to own Grace gear, I was also thrilled to find that they incorporated the very attractive trademark Grace bezels around both headphone jacks.
- The volume control, which also serves as a press-down control knob to access the m9XX's various options, has Grace's trademark feel, subtly (and silently) clicking under my fingers as I turn it--it's a lovely, premium feeling control.
After I settle back into the office, after a few more miles with the m9XX, we'll shoot a Head-Fi TV episode that includes it and says more about it, as I'm very excited about m9XX in early use. I'm thrilled to finally own my first piece of gear by Michael Grace and Grace Design! It's about time.
Check out Massdrop's drop on the m9XX by CLICKING HERE or on the photo below:
(Above) Shure KSE1500 Sound Isolating Electrostatic Earphone System with Grace Design x Massdrop m9XX.