Nowadays, there's more headphone-oriented gear on the market than you can shake a stick at. Headphones are abundant. Headphone amps come in a wide variety of styles, prices, and topographies. And plenty of DACs now feature quality onboard headphone amplification. It's a headphone lover's dream.Things were not always this way. Go back about 10 year, and there was far less of.... everything. In particular, if you wanted a quality all-in-one DAC/headamp solution, choices were rather limited. The major contenders came not from audiophile brands but rather the pro audio world. We had the Benchmark DAC 1, the Lavry DA10, the Grace Design Model 901, and - to a lesser extent - the Apogee Mini DAC. All offered what was considered at the time to be exceptional D/A conversion, with at least a reasonably nice headphone output, in a decidedly pro-audio oriented package. And the price on most of these approached $1k which was not a small sum back then. The Grace Design unit set itself apart by selling for $1,500 and by referring to itself primarily as a headphone amp - D/A conversion was also part of the deal, but the lack of analog outputs meant headphones were the only way to listen.At the time, I cycled through all four models in my search for headphone bliss. I quickly eliminated the Apogee as being sub-par compared to the trio of Grace, Benchmark, and Lavry. All three models had their strengths and weaknesses, such that I enjoyed them all in their own way. This was a hot topic on forums at the time. It seems like many headphone enthusiasts were coming to the same conclusions I was: the Benchmark was crazy detailed but somewhat bright and unforgiving. The Lavry was creamy smooth and could be described as the most "analog" sounding. The Grace was perhaps the most balanced of the lot. All three models had their fans and a few detractors too, as is usually the case with most gear.The m901 was my favorite option for driving my reference headphones, which at the time consisted of models like the Audio Technica L3000, Grado RS-1, and of course the Sennheiser HD600 which was standard issue for enthusiasts back then (and probably still should be). I wasn't in love with the 901's DAC portion, but the headphone stage was phenomenal. I often paired the Lavry as DAC with the Grace as amp, playing to the strengths of each model. Then along came the Grace m902 which I felt significantly improved the DAC section. While perhaps still lagging slightly behind the Lavry, it was close enough for me to sell the DA10 and stick with a one box solution for a time. It was also novel in having a USB input with which I took my first steps in computer audio. Very few devices had USB inputs at that time. But as other stuff hit the market I eventually moved on - you know how it goes. Grace had success with their m903 and more recently the m920, both of which seemed competitive in their field. I have heard both but not extensively. My point is, Grace Design has made catering to us headphone enthusiasts a priority for over a decade by now, so they have some expertise on the subject.The range between $1,000 and $2,000 is jam packed with killer DAC/headphone amp combos. I'd say that's probably where you'll find the best value, in terms of gear that approaches state of the art but doesn't cost more than a new car. As you drop lower than that, it becomes more of an exercise in priorities. I'm not saying there aren't some solid devices out there. There's just usually some sacrifice involved. Maybe the headphone out isn't all that great. Maybe the USB implementation isn't on par with the alternatives. Maybe the amp does great with full size cans but doesn't play well with IEMs, or maybe it's the other way around. The trick is figuring out how to minimize weaknesses while packing in all the stuff us HeadFiers want most. Not a lot of devices nail those objectives.One option, however, recently made its way to my audio rack, and it's worth talking about - the Grace Design m9XX . The product of a joint venture between Grace Design and Massdrop, the m9XX will go for $499 and should be available to order in a few days. It's a Massdrop exclusive, just like the AKG K7XX which I enjoyed so much - bonus points for sounding marvelous when paired together.Now, for $499 I don't expect miracles from an all-in-one device. Typically we might get a pretty good DAC with a mediocre headphone amp, or vice versa. Not this time. The goal of the projects seems to have been packing most of the audio magic of the m920 (which at $1,999 is very highly regarded), stripping away many of the potentially unnecessary features, and ending up with a killer, somewhat minimalist device which performs way above its price.While the m920 and previous generations were all half-rack sized (just like the Benchmark gear and many other popular DACs), the new m9XX is a compact little thing. At 4 inches wide, 5.25 inches deep, and less than 2 inches tall, this thing takes up very little space. Which makes it perfect for desktop duties where a larger device just wouldn't fit so well. I called the m9XX "somewhat" minimalist because, while it may lack quite a bit compared to the m920, it still has a reasonably advanced feature set considering the compact size.Let's explore: on the input side we get XMOS-based USB capable of hi-res PCM as well as DSD64 and DSD128. There's also a Toslink input with the usual 24/96 cap. Outputs come in the form of RCA line-out as well as dual 1/4" headphone jacks, one of which automatically mutes the line-out when a headphone is inserted. Notably, Grace includes their proprietary crossfeed option for those who might find it appealing. This is a welcome feature as not many devices in this price range have the option. And Grace's crossfeed implementation has always impressed me, being less heavy handed than most - I find it particularly useful with older recordings using hard-panned mixes which clearly favor speakers over headphones, but it's subtle enough to use on modern mixes if the mood strikes. With certain headphones and music, it really does help bring the recording further "out of head", while in other cases it isn't as useful.And that's about it. There really isn't much more room to add inputs or other options even if Grace wanted to. As it stands, they had to use micro-USB connections to save space. Yes, I said connections in the plural.... let me explain. The right side is what I'd call a "normal" USB input. It handles both power and data, allowing me to use the m9XX with my Surface Pro 3 without a mess of cables. This configuration gets us what Grace calls "low power mode" which delivers something like 160mW per channel RMS into a 32 ohm load, and roughly double that into 50 ohms. This is plenty for your Grado, Audio Technica, Ultrasone, and other sensitive headphones, and more than enough for pretty much every IEM on the planet. I also believe Grace Design is being careful not to boast using peak power, which is often done by marketing departments. If they wanted to sound more impressive they would mention the peak output for a single channel which is quite a bit higher. Need more power? That's why Grace supplies that extra USB input. By adding a second USB cable for power and using an adapter similar to a cell phone charger, the m9XX jumps up to over 1,000mW per channel at 32 ohms. Now we can run most planar magnetic headphones with very satisfying results. And with a corresponding boost in voltage we also get excellent sound with higher impedance models from Sennheiser and beyerdynamic. Again, very impressive considering the compact dimensions of this thing.Let's talk user interaction, as I find it very well done here. The entire top of the enclosure is reserved for the multi-function knob which spins and presses to accomplish volume control and option selection. Hold it down to access the menu, which leads to options like crossfeed, startup volume memory, and 4 selectable digital filters. The display is a simple two-digit LCD with another small dot being used to indicate "on" or "off" for a function - see my pictures to help illustrate. It's a surprisingly simple yet effective system which I got the hang of immediately. The volume knob reminds me a bit of the old Ortofon HD-Q7 amp, which is quite a compliment with respect to aesthetics and usability. In fact, this entire design is somewhat reminiscent of that under appreciated little amp, which I've always felt absolutely nailed the design portion if not quite the sound quality category. The large button/knob on the m9XX is very precise, matching perfectly with the volume adjustment which is handled in .5dB increments. Overall the m9XX is a joy to use which isn't something I can say about every DAC, including some expensive models.The heart of the DAC design is AKM's flagship AK4490 chip. This is a fairly new model, released within the last 2 years or so, and is not all that common as of yet. HeadFi folks probably recognize it most from its recent appearance in the updated Schiit Bifrost DAC where it replaces the older AK4399 used in the first gen model. It also shows up in the new (and rather expensive) Lindemann Musicbook series. Aside from those two brands, I'm not aware of anyone else using it thus far. AKM DACs in general don't seem to be used as often as Wolfson, Cirrus, TI, and ESS, so it's hard to know what to expect. Of course, the DAC chip itself is only one small piece of the puzzle, so maybe it's best we don't come into this with preconceived notions anyway.I already mentioned the XMOS USB implementation, which ends up processing the Toslink input as well. A unique hybrid analog-digital phase-lock loop system (PLL) helps reduce jitter which is especially useful for Toslink, being more likely fed by a lesser source such as an Apple TV. Extensive power filtration is employed to make sure the noisy USB connection isn't fouling things up. Grace uses a total of 5 power supplies including separate supplies for the XMOS implementation, the DAC, and the analog stage. 5V USB power is converted and augmented by a proprietary system allowing the device to run +/- 9V rails on basic USB power, and +/- 14V when running in high power mode with the power adapter. I won't go into it too far but again this shows the expertise involved, especially for a small and relatively affordable device such as this.The headphone output is built around a Texas Instruments THS6022 transimpedance/current feedback amplifier. I have not seen this particular chip used in this application before. More typically, we see chip amps based on either the TPA6120A2 (quite powerful but usually requires 10 ohm output impedance for stability) or the TPA6130A2 (stable at lower output impedance but far less powerful). Nothing wrong with either, but I was pleased to see something unique being used which seems to combine the best of both the TPA options. Output impedance is well below the magic 1 ohm mark - at 0.08 ohms, listeners have nothing to worry about even with IEMs sporting wacky impedance curves. And I already mentioned the output which is very robust indeed.Now, after all that, how does the m9XX perform? In my humble opinion: it's really something special. Neutral, resolving, clean-as-a-whistle, the m9XX is an excellent monitoring tool. Paired with a nice set of active monitors, this setup allows one to hear deep into the mix, with a level of transparency few compact DACs can match. It pairs quite well with the AMT tweeter in my Adam Audio F5 monitors - a tweeter known for its expressiveness, not to mention ability to expose sources with poor timbral accuracy. Top end air and extension are without reproach, making it hard to believe this DAC/speaker combo sells for just a bit over $1k. I've heard big rigs using expensive/exotic speakers which utterly failed at reproducing the brassy tones of a trumpet, the shimmer of a crash cymbal in all its glory, or the quick attack of a piano strike The m9XX/Adam F5 combo excels in all three of these tests, proving one needn't spend a fortune to achieve lifelike sound.Despite its clarity, I wouldn't necessarily characterize the m9XX as a clinical, dry sounding DAC. It's got enough resolution to pull out gobs of microdetail, but it also maintains a connection with the music which is lacking in many pro-audio style DACs. The result is closer to what I remember from the old Grace 901 - balanced, organic, well rounded, not lacking in detail but not shoving it down your throat either. I actually think the little m9XX would compare favorably with the original 901 in terms of DAC performance - that would be a fun comparison if I still had a 901 around. Unfortunately I don't, but I do have several more recent DAC comparisons which might help illuminate the flavor of this device.The Parasound Zdac V2 ($549) is a very enjoyable DAC. It falls on the warm and smooth side, with a dynamic punch that may exceed what the m9XX can offer. In contrast, the Grace unit is more resolving, cleaner, and more airy in tone, with a more precise soundstage and accurate imaging. I really like both models and would choose among them based on what associated gear makes up the system.The Rega DAC-R ($1,195) is also a warm and smooth DAC, but I find it troublesome in that it lacks the dynamic bombast of the Parasound, while going even farther into warm/smooth territory. Consequently, it feels like a wet blanket, where music just plods along with no emotion. It can be helpful for taming bright systems but that's about it. The Grace m9XX is superior in most every way, to the point of this really being no comparison. I know a few people who really enjoy what this DAC does, but I just don't hear the appeal based on extensive listening. Maybe my unit is a dud.The Musical Fidelity MX DAC ($999) is the first Musical Fidelity product I've actually enjoyed in quite some time. I'm told there's been some restructuring at the company and some new blood brought in - hopefully this brings about good things, as Musical Fidelity used to be a big player in the headphone world with their compact X-series components. The MX is a very pleasant DAC where nothing stands out as objectionable - a good thing considering the funky performance of the previous M1 DAC and its variants. The more I listen, the more I like it, and find it very similar to their $2,500 M6 CD player I used to own - perhaps even better. By comparison, the m9XX is just as transparent, just as engaging, and at half the price, is a far better value. And that's before we consider the headphone amp functionality. Bottom line is that I really can't tell these two apart, so there's no way I'd spend double on the MF product, despite it being a very competent offering. If you needed balanced outputs or wanted to stack with the Musical Fidelity MX-HPA headphone amp, the Grace wouldn't work as well, but that's about the only situation I can think of where I wouldn't get the smaller m9XX and call it a day.MicroMega's MyDAC, at $399, is one of the few devices here small enough to look like a direct competitor to the m9XX. Unfortunately it sounds like there were some compromises involved in achieving this small form factor and low price. It has a focus on transient attack which initially makes for an exciting sound signature, but ends up overwhelming with a busy presentation that becomes unbalanced during long term listening. This is one of those devices that you first demo and think "Wow, I love it!" but later come to hear as fatiguing. The m9XX initially seems a tad boring in comparison, with its measured, even-handed approach. Where's the bite, the snap of the music? After a short time it becomes clear that the m9XX is actually more lifelike, more organic, while the MyDAC is a neon facsimile of reality. This thing received some rave reviews a few years back, and I actually believe those reviewers were genuine in their assessments... they just threw the device in the system, listened for 20 minutes, wrote it up, and moved on. That's why I spend as much time as possible with my listening, sometimes even missing the window of new-product-buzz. I like to be confident in what I'm hearing and that sometimes takes longer than you'd expect.$500 doesn't buy all that much performance in absolute terms... and when it does, you're typically looking at a dedicated DAC or headphone amp by itself rather than a combo unit like this. So how about that headphone output - is it compromised as we might expect for the price? Thankfully, no. The m9XX sounds very satisfying driving headphones directly. Just like the DAC portion, it strikes an excellent balance between accuracy and musicality, and pairs well with nearly every headphone I have on hand. I'm actually rather surprised at how well it does considering the size of this little box. Apparently Grace knows their stuff.Straight from a single USB connection which translates to low power mode, the headphone out is exceptional with IEMs. I get a mild, very tolerable hiss with my EarWerkz Supra, JH13 FreqPhase, and Unique Melody Merlin, which my brain easily filters out once the music starts. The rest of the IEMs in my collection play with an essentially silent background: Noble Audio K10, 5C, 4C, and Savant, Dunu Titan, Lear LCM-5 and LCM-BD4.2, the Aurisonics AS-1b, and many others which I'm forgetting at the moment. A volume setting of roughly 50 (out of 99) is typically good for most music, leaving plenty of room to dial in more or less as needed. I'm a huge fan of custom IEMs and it can be frustrating when so many amps - somewhat counter intuitively - can't handle these easy-to-drive little things. I'm happy to report the m9XX passes the test with flying colors. A top-level CIEM can be as resolving (arguably more so) than the best full size headphones, and will often expose weaknesses in a source. Again, the m9XX passes the test with aplomb.Moving to full-size headphones, the m9XX does a very competent job as well. As I mentioned earlier, some models do just fine in low power mode. The Astell & Kern AK T5P, a rather sensitive flagship closed back headphone, is extremely enjoyable with the m9XX set to volume 60-70. If this was my main headphone I wouldn't ever use the high power mode. Same with the Grado PS500 and the Sony MDR-1A. Of course, driving current-hungry planar magnetic cans like the Audeze LCD-2 provides an obvious excuse to run that second USB cable with the power adapter. Note that gain remains the same, but drive is enhanced. So running the LCD-2 in low power mode with the m9XX already gets me all the volume I could ever need. But the bass performance is weak, and the midrange lacks focus. The whole thing is just soft and squishy. It's clearly underpowered. High power mode doesn't suddenly let me run at lower volume settings, but it does give a clear increase in drive. The LCD-2 regains its authority, with deep, clean low notes and a more insightful midrange. This same experience applies with the HiFiMAN HE-500 and Mr Speakers Alpha Dogs too. There's enough juice on tap in high power mode to get most planar magnetic headphones jumping, with the usual exception of Hifiman's HE-6. I also prefer high power mode with my Sennheiser HD650 and other high impedance models. Interestingly, I even prefer high power mode when driving the AKG/Massdrop exclusive K7XX. It's not the most demanding headphone out there but seems to really "wake up" in response to the extra power. It's handy to have both options available.Overall the amp section is nearly identical to the DAC - both are clean, transparent, and highly resolving, yet not analytical or dry. The end result compares favorably to any number of more expensive devices I can think of. The original Benchmark DAC 1 for example, is more chalky and etched sounding to my ears, with a glare to the upper mids and a thin character that just don't enjoy these days. When it first launched back in the day, I admit to being taken by its seemingly extreme resolution, but I eventually began to hear it as artificial and obnoxious. Their DAC 2 is far superior to its predecessor and does manage to outclass the m9XX, as it certainly should for the price. The delta is not as large as you might think though. I also prefer the m9XX to the Mytek Stereo 192, which to my ears sounds dangerously close to the original Benchmark DAC 1. The Grace model has more life and soul, sounding better no matter what headphones or speakers I pair it with. The best comparison I can probably think of is the Anedio D2 which was selling for $1,249 last I checked, down from the original $1,470. The little m9XX gives a huge portion of the same ultra-transparent, open-window type of sound, at a far lower price and in a smaller package. I still find the D2 superior but spotting a difference requires some careful listening with excellent recordings - most people would find them very similar under normal circumstances. Those who know my opinion of the Anedio will understand just how big a compliment this comparison really is.I never intended to turn this into such a long write up. I've got paid articles in progress for InnerFidelity and Part Time Audiophile which I really should be focusing on. But this little device gets me optimistic about what can be achieved through smart engineering and knowing what users are looking for - and what they aren't. Grace Design seems to have whittled down the technology and features of their far more expensive m920 in just the perfect way, while Massdrop allows it to be sold without a huge dealer markup. The initial drop is limited to 500 units and I suspect those will go very quickly - I'm hoping (though I have no verification at this time) that Massdrop will offer more drops in the future just as they have done with the K7XX. In any case, here I am rambling on and on about it instead of working on my "real" articles. Jude will have his say on the m9XX, as will several other experienced HeadFiers, so we'll see if my experience matches theirs. All I can say is that I'm thoroughly impressed by this thing, and think it might be a new benchmark (no pun intended) in terms of sonic results for the price.