Hey guys, im not sure if ill be any help as this is my first step into the audio world, but ive had the cma600i for a few weeks and ill try to give some useful information.
Shipping packaging:
I was looking for an excellent amp / dac that would allow me to concentrate on headphones and carry me until i discover my preferences in sound. I bought this from moon audio and it was a problem free / pleasant experience. Shipped fast , well packaged and came in perfect condition with a power cord, controller and a certificate of authenticity. The certificate also shows test results done by Audio Precision of frequency response and amp power tests which match the graphs on their site.
Audio setup:
Im playing files from my PC foobar2k -> usb > cma600i > ath m50x / hd 650 single ended. Many files from lower quality recordings to higher quality recordings.
Ive also tried using pre amp with a logitech z906 system thru the RCA connectors ( not active but i think it is considered a powered speaker setup). In the future i plan on getting a tube amp to run from the pre amp.
Experiences:
I dont really have much experience with other amp/dacs, so ill just try to explain my experience with this unit. Ive done a bit of research on different headphones trying to get a feel for their sound signatures and decided to start with the hd 650s. The 600i had no issues powering either of these sets and definately lifted the "veil" on the hd650s. It allowed the characteristics of the headphone to shine with no interference that i could hear. Ive listened to many different styles ranging from fast guitars / drums in death metal to solo piano music. I found myself completely immersed in the music because all you could hear is the music. On those quiet solo piano pieces you could hear each key stroke float through the air and decay with no static or hissing noises clouding the music. Bass felt the way it was intended to be ,impactful, not over powered or under done. The warmth helped tame the treble and made alot of lower quality recordings more palatable ( with the hd 650). On the down side i tried using the m50x to see if it changed its sound at all. I found that the short comings on the m50x became more apparent with the amp. Very tinny shallow sound and highs were very bright and cold, it was almost unpleasant going from the hd650 to the m50x. It became apparent to me, that this amp was very clean and really allowed the headphones to shine.
I had a few negative experiences when using the amp/dac for gaming and general purpose use on computer. When sound was routed through the 600i, sometimes i would hear a system sound or pop-up sound with a very unpleasant click/hissing sound. This only seemed to happen when i had no audio for a while and the notification would pop up. I also had a situation arise when i was playing Overwatch and using voice chat over the Discord application. Every so often i would hear a click, audio would die and come back a few seconds later. I didnt buy this amp for this purpose so its not a big deal for me, just something i noticed while testing it out. I wasnt able to successfully replicate the audio dying, so im not 100% sure if it has something to do with win10/software , PC mobo sending audio via usb or if its the amp.
Other notes:
Ive read that many amps can get pretty hot during operation and this unit does not get that hot even after hours of use. My computer room can get pretty hot, so its nice that this doesnt add too much to the heat. I really love the design of this amp, it looks great with neutral bluish greyish coloring. Its flat and wide so i have my monitor sitting on top of it with no issues. The dial and switches feel solid and of high quality. The controller is pretty nice, there is a servo motor on the volume dial so if you use the controller to change the volume you can see the dial move.
This setup is amazing, once i start listening to music the immersion takes over and its so easy to lose track of time. I have no regrets with my purchase and im looking forward to pairing more things with this amp. I have a custom balanced cable coming for the hd 650 soon, so im looking forward to trying that out. Im also planning to get an lcd 2 at some point. I didnt do much testing with speakers.
I mostly listen to metal, ranging from the various sub genres of black metal to folk metal. I tested a little bit of vaporwave/ future funk and synthwave.
Hopefully this helps shed some light on something you guys are curious about, sorry i dont have more experience to compare this too also wall of text >.>