Amp comparison time!
I have now owned the Audioquest Nighthawks for around 8 months. For the first 4 months I drove it with an Audioquest Dragonfly (v1.0), and for the next 4 months I drove it with a Grace Design m9xx.
I can confidently say that I love both amps. At first, when I switched to the m9xx, I expected a complete upgrade; all aspects of sound to be better in every way. I realize now how that expectation was unreasonable. Every album is different, with a different production style that highlights certain aspects of certain amps. The following is a comparison between the two amps, with thoughts on various aspects of sound quality for these different recordings.
Grace m9xx:
This is a fantastic amp that sounds good with the Nighthawk on almost every recording. The highs are very natural and detailed compared to the Dragonfly 1.0. Some recordings that are unlistenable on the Dragonfly because of high treble presence and importance in the music (ex. Jordan: The Comeback by Prefab Sprout) sound quite pleasant on the m9xx. The best way I can describe it is, when you hear a high-pitched sound on the Dragonfly, you don't know what it is. It hits your ear with a crackle and your brain has to work to recognize the instrument. With the m9xx, it enters your ear and you know, "Oh, that's a synth playing a sawtooth wave."
The single best-sounding album I've heard through the m9xx-Nighthawk combo is On Land And In The Sea by Cardiacs. The album's EQ matches perfectly, and the m9xx can really handle the energy put out by Cardiacs' flavour of prog-punk, keeping you engaged with each and every emotional outburst. By the time it's over I feel equally exhausted and happy.
In many ways, switching to the m9xx was a great relief. I grew tired of the Dragonfly's flaws—the detail retrieval was lacking, especially in the treble region, and it had a bad handle on energetic music. The m9xx performs these tasks quite well. However…
AQ Dragonfly v1.0:
The Dragonfly wipes the floor with the m9xx at three things: bass, macrodynamics, and soundstage. Any recording that masters one of these elements of music reproduction will sound great on the Dragonfly, so long as it doesn't also highlight any of the Dragonfly's glaring flaws. Let's look at a few examples:
For bass: Irresistible Bliss by Soul Coughing.
What a funky record. This album really highlights the beautiful bass on the Dragonfly, rocking the house and making the Nighthawks come alive. Sebastian Steinberg's bass playing captures my imagination with its neverending genius, and I start to feel things I never before imagined were possible from the sheer unstoppable power of those notes. Not to mention how the frequent keyboard interjections highlight the Dragonfly-Nighthawk's excellent soundstage properties, creating sheets of fragile beauty for textural/emotional contrast. And the drums are played with great dynamic prowess, coming in and changing things up at all the right times to drive the songs forward. The mastering on this album is a perfect match.
For atmosphere: I Don't Like ****, I Don't Go Outside: An Album By Earl Sweatshirt.
I didn't get this album until I heard it on the Dragonfly-Nighthawk. The dark, sparse production transports you to an entirely new world with incredible emotional potency. Every texture is placed just so, and the Dragonfly makes you care—the exhaustion and darkness overwhelms. On the m9xx, it doesn't feel special—I'm not emotionally involved like I should be. Unfortunately for the Dragonfly, there's one particularly grating high pitched sound in the song Grief that hits the amp where it hurts. God, that sound is so painful on this setup. But it doesn't matter because the atmosphere on the rest of the album sounds so good.
For macrodynamics, and everything else: Plastic Beach by Gorillaz.
Listening to this album on the m9xx is the saddest thing, because I KNOW what Plastic Beach is capable of, but the m9xx just ruins it. Plastic Beach-Dragonfly-Nighthawk is the single best album-gear-headphone match I've ever heard.
First, the bass—in just the second track, you get multiple layers of pungent synth bass that extends REALLY deep. Bass quality is consistently mesmerizing throughout.
Second—the soundstage. Every little synth extends into infinity all around you in a beautiful dance of perfection. It's like standing on a rock in the middle of a foggy lake with sound coming from every direction as far out as your ears can perceive it.
Third, the macrodynamics. That swell in Empire Ants is one of the most euphoric moments in music history. It starts to get louder, and you think, "Woah, this is getting intense," and then it starts to transition and you think, "No way is it going to get as loud as I think it will," and then the bass comes in and it's even louder than THAT. It just captures my complete, devoted attention in a way most albums can only dream of.
One more moment: in Some Kind Of Nature, a sad choir reveals itself out of a gigantic wall of synths and piano and the gravity of the realization feels nothing short of religious. Okay, I'm done now.
In short, the Dragonfly is a fun piece of hardware that has bursts of brilliance despite significant limitations which make many albums hard to listen to, while the m9xx is a consistently well-performing device with middle-of-the-road bass quality and soundstage, but incredibly pleasing treble detail. I like the m9xx a lot more overall, so I need a really compelling reason to go back to the Dragonfly now that I'm used to decent microdetail. But sometimes I feel like being blown away and it's hard for an all-rounder amp to do that.
I hope this helps Nighthawk owners considering one of these amps in the future.