Mini, incoherent review of the iBasso DC04Pro since I just buy audio and don't really describe it well
It came bundled with a type-c to type-c cable, type-c to lightning cable and a type-c to A adapter. The finishing on the aluminium and the tempered glass is well done and feels very well built.
With only my desktop stack and my DAP (see signature) to compare it to, I can say that the DC04 Pro is quite straightforward in the listening experience with a potential tilt towards the highs. The word that came to mind with my initial listening was "sharp", some K-Pop songs such as "4 Walls" by fx caused me a little discomfort at first with female vocal high notes as they were noticeably "sharper" and more pronounced than my Hiby R5 Saber.
Otherwise, I feel that they present the low-end and mids with tremendous clarity and linearity. I feel that the overall signature is very detailed if a little lean for my ears currently (noting that I just got the dongle and have been listening to "warm-neutral" IEMs for the last several months). Overall I feel that they work very well for a good critical listen where you're trying to extract minor details in a well-recorded song and less so for a relaxing background music mood type of listening.
In more technical aspects, the noise floor is no joke, touted by iBasso to be 0.9 microvolts, I am unable to hear any audible noise looping a 'silent' track on my Campfire Andromedas in a quiet listening environment until I get to volume levels that would cause hearing damage or driver damage.
For the app (and lack thereof for Apple devices), the filters do subtly change the sound signature, with the aforementioned song being less sharp and sibilant on the ears with the slow filter or NOS on. I believe using it on an iOS device defaults to Filter No.1 and Turbo mode and therefore if you're particularly sensitive to high end sibilance than I would factor that into your decision. I don't think I will ever turn off Turbo mode, turn on Eco Mode nor am I using these with headphones on a regular basis, so your mileage may vary.
Overall, I think the DC04 Pro presents a rather compelling package and I'm pretty happy with the purchase. Almost black background, sharp and detailed, I will be utilising this for critical listening sessions and when I'm using particularly sensitive IEMs.