I'm new to Head-Fi, so I apologize in advance for information that isn't useful or pertinent. The Audioengine D1 is the focus of this thread, so I hope "Dedicated Source Components" is an appropriate categorization.
I am running a Mac Mini via USB to the D1. The D1 is connected to the Airmotiv 4s via Blue Jeans Cable RCA cables. My music collection includes a variety of quality when it comes to files (128, 256, 320, and ALAC).
Emotiva Airmotiv 4 - I am pleased with the performance of these monitors directly out of the Mac Mini. The basis of comparison is my extensive use of Aiaiai TMA-1 headphones. Compared to these headphones, the monitors offer a wider soundstage, more balanced sound (the TMA-1s are darker), and engaging mids and highs without being shrill or overly bright. Lastly, the monitors offer better stereo imaging. I have them angled toward my ears with Audioengine's DS2 speaker stands which fit nicely.
My friend has Audioengine 2s. I did not compare these in an A/B setup, so my comparison is from memory. I feel that the Emotiva monitors offer more accurate and satisfying mids and highs. The low end of the Audioengine was very prominent, but also seemed colored compared to the Emotiva monitors.
The build quality of the Emotiva Airmotiv 4s is great. My one complaint is the dual volume controls. Each monitor has its own volume knob which feels very flimsy. Compared to the solid power button on the rear of each monitor, the volume controls feel like they will break when I adjust them. I find myself obsessing over whether the volume controls are coordinated between the monitors (I knew this might bother me before purchasing them, but took the risk). I worry that this could affect imaging. This lead me to purchase the D1 as a means of controlling volume in a more predictable manner and hopefully improving sound quality with an external DAC.
Audioengine D1 - The D1 does not have any gain switch, which is an issue out of the Mac Mini. It is way too loud, since Emotiva recommends maxing out the volume on the Airmotiv 4s and using a DAC or similar piece of equipment to control volume. Because of the gain issue, I am back to obsessing over adjusting the volume exactly right on each monitor. Even with the monitors dialed back, the gain is very high on the D1. This is not a deal killer, but mainly a nuisance. I might try out line level attenuators, but I am not sure if they will affect sound quality.
Sound quality: I am disappointed to say that in flipping back and forth between listening to the Emotiva monitors directly out from the Mac Mini and through the D1, I cannot really discern much of a difference. Even more concerning is the fact that I think I hear some files clip/distort slightly through the D1 that do not clip directly out of the Mac Mini. I have tried the D1 out of a Macbook Pro and experienced the same thing. It is minor and I only notice if I listen critically, but I am not happy with an external DAC that possibly lowers sound quality. Also, stereo imaging seems slightly less immersive and the sound is a tad thinner.I though there might be more bass extension with the D1, but it turned out to be wishful thinking.
As I mentioned before, I tried the D1 with another source (Macbook Pro). I also switched up the USB port with no improvement. I have disconnected and reconnected everything and restarted all components in the chain. Audioengine recommends 40-50 hours of burn in, though I am highly skeptical of the need to burn in a DAC for more than a few hours (I understand certain speaker components such as drivers need to loosen and settle, but I don't really see how the compents in a DAC would "settle" or "loosen"). Nevertheless, I allowed for a burn in period of around 10 hours. I also ordered a Toslink to Mini cable so I can try S/PDIF out from the Mac Mini instead of USB (though I am doubtful I will hear any difference since I don't hear crackling or popping that a bad USB connection might produce).
So, am I completely out of my mind?
I don't think there is anything wrong with my D1, since the issues are not glaring. I should have researched the gain issue more before purchasing, so I consider that my fault. But, the fact that the D1 does not improve the sound quality of the Mac Mini is definitely disappointing.
What do you think?
Thanks for any comments you can offer!