Big thanks to Josh and Kyle for loaning me these units for review.
Rather than just review the Fulla 2 as I was originally intending to do, I decided to reach and and see if I could get a couple of different options to get a better feel for the $100 price bracket. Luckily, I managed to obtain the Audioquest DragonFly Black and the Monoprice Desktop Amplifier as loans from Kyle to compare to the Fulla 2.
Schiit is a company with products that perform well in their price brackets, an entirely US presence, and clever marketing. As a result, Schiit has become a go-to brand and recommendation for many in the hobby. The Fulla 2 is the sequel to their original USB powered, portable DAC/Amp combination unit, the Fulla. The Fulla 2 improves on its predecessor in a few ways, adding analog preamp functionality, fixed line outs and variable pre outs, two USB ports for power and data, and replacing the ⅛” headphone jack with a ¼” jack, presumably meaning it’s meant to drive full size headphones. From my use it seems the that the two USB ports are really meant to power the DAC/Amp or the preamp respectively.
Monoprice has long been a destination for reasonably priced, well built products, especially audio cables which can become quite expensive. Recently Monoprice seems to have advanced their efforts in the audiophile headphone market, especially with their new Monolith line of products. Their first real product that focused on this category was their all in one headphone DAC and headphone amplifier. The Monoprice Desktop Amplifier has a very similar case design and connectivity to the Fiio E09k desktop headphone amplifier, adding an integrated USB DAC. The unit offers similar features to the Fulla 2, but because of its larger size offers more standard RCA connectors for Line In, Pre Out and Line Out, a gain switch, and uses wall wart for power instead of strictly being powered over USB.
Audioquest is a brand mostly known for its audiophile cables and in the last couple years expanded their offerings in the audiophile headphone market to include the Nighthawk and Nightowl headphones as well as their line of portable USB DAC/Amplifiers in the DragonFly series. The Audioquest DragonFly Black is the smallest and most portable of the three, featuring no external hardware controls, and essentially looks like a USB drive with a 3.5mm output that can be adjusted to work as either a DAC Line Out or a headphone output. This DAC/Amp does not feature any analog input or pre functionality but exchanges that for its significantly more portable form factor.
All three of these units were tested with the HD800 and Audeze LCD2. USB for each was connected to a powered hub to minimize USB power issues. WASAPI output was used to test each of these units.
Schiit Fulla 2:
I find the Fulla 2 to be generally clean, even, and smooth sounding without any obvious tonal colorations. It has the gain to get quite a few headphones loud, but when faced with challenging loads is not able to muster the power to really fill out the low end on headphones with large impedance swings in the bass region. For example, when testing with the HD650 and even with the HD800, I found the midbass wasn’t as present or punchy as I would normally expect and seemed a bit under-driven. While I find the tonality free of issues, the sound of the Fulla 2 feels sort of flat. The staging seems sort of flat but wide, arranging everything in a line and not imaging them in clear relation to one another. Small impacts in music like those heard from acoustic guitar strings or the reverberation of drums seem to get lost with the Fulla 2. In general, impacts don’t feel as sharp or well defined as they should, and seems to be true regardless of whether you use the internal DAC or the line input of another source. That said, I find the clarity of the unit is quite good, and don’t hear the lack of impact as a general fuzziness or haze to the sound. The unit also does not take well to outputting a line level signal and driving headphones at the same time and will distort both significantly, even with both USB ports plugged to data ports and wall power respectively. I believe the Fulla 2 uses a USB Class 1 audio controller that allows it to connect without needing drivers to all operating systems including Windows (which still does not support USB Class 2 audio). When trying to connect it to my phone, a Nexus 6P, I found that my phone was not able to supply enough power, but that by plugging it into wall power as well, I was able to use the unit with my phone.
Monoprice Desktop Amplifier:
In comparing the performance of different headphones on the Monoprice Desktop Amplifier (MDA), one issue I noticed immediately was the output impedance. At 10ohms it seemed to have a clear effect of increasing the amount of midbass on dynamic headphones with large impedance swings. I general I found the MDA was able to deliver that additional bit of power to fill out the bass, exaggerating it on headphones with large impedance swings in the bass region. Overall I felt that small impacts were also clearer and better defined than on the Fulla 2, however despite this, the sound seemed more distant and hazy than on the Fulla 2, this seemed especially apparent with male vocals. This distance also seemed to give the effect of slightly larger staging, though I did also feel that imaging was a bit more coherent over the Fulla 2 and presented a bit more depth. The MDA also seemed to have a slightly warmer overall tonality, which again may be attributed to the higher output impedance. In testing with my Audeze LCD2, I still found the unit to sound a bit less present in the treble and exaggerated in the bass, despite the LCD2 not being affected by output impedance due to its flat impedance curve. This lack of clarity and warmer tonal balance was also present when using an external line input into the MDA as well. In terms of connectivity, the MDA plugged and played without issues on my Windows 10 desktop and on my phone without the need to install any additional drivers.
Audioquest DragonFly Black:
I felt the DragonFly Black actually had a lot of similarities to the Fulla 2. I felt that all but the most sensitive headphones felt slightly under-driven and flat sounding, lacking some of the detail and clear impact of strings. This is no surprise seeing as the DFB is the weakest of the three, having a power output of only 45mW @ 32ohm (vs Fulla 2’s 360mW and MDA’s 900mW outputs respectively). I also felt that tonally, there were no major balance issues present in the sound. In addition however, I felt that the DFB wasn’t as smooth as either the Fulla 2 or the MDA, having a grainier, harsher sort of texture to its sound that may have also masked some of those quieter, smaller impacts in the music. I also found vocals to have a sort of unnatural hardness or glare that seemed to exaggerate some of the harshness of sibilants especially in female vocals. Staging of the DragonFly Black was quite flat and upfront compared to either the Fulla 2 or the MDA and imaging and separation of instruments wasn’t as clear as the Fulla 2. I wasn’t able to easily identify layers of depth to the stage and things seemed quite close and a bit jumbled together. Connectivity was simple with the DFB, again requiring no driver installation to get working on my PC. My phone was also able to provide enough power for the DFB as well.
I think in the $100 range for DAC/Amps, like the $200 range for headphones, there are some choices you’ll need to make in terms of your functional needs and preferences, and there are certainly some qualities you’re going to sacrifice for others based on your order of priorities. I find the DragonFly Black to really be the one that clearly trades some functionality and performance for real portability as I don’t feel either the MDA or the Fulla 2 are truly portable solutions. That said, I personally can’t find a situation where I would want to use the DFB over the regular output of my device unless that output is truly problematic. As desktop solutions I think the Fulla 2 and MDA trade blows because of slightly different sets of compromises. With the MDA you get a slightly more impactful but less clear sound, and you also have to deal with the effects of the higher output impedance and overall tonality. With the Fulla 2, you gain some clarity, you lose the output impedance issues but you also lose some of that physicality and impact to your music. I think it’s hard to really point at any of these units as a clear winner over the other because they all require accepting different kinds of compromises that are going to depend on your use case and preferences. For example, someone preferring a slightly warmer signature and looking for an amplifier to pair with planar magnetic headphones, I would likely recommend the MDA. For someone with a dynamic headphone looking for a more balanced signature, I would likely recommend the Fulla 2. For someone looking for an extremely portable solution to power their IEMs because their devices output is poor or has a high output impedance affecting the sound of their headphones, I might recommend the DFB. In that way, I think that all three of these products fill different niches and all perform about equally at this price point for those different use cases.