The AK SP3000 is indeed a pleasure to use. I was fortunate to have it on loan for a few weeks, from a friend of mine that is not a seasoned audiophile, but he wanted the best portable device he could currently buy. I compared it to my Hugo2/2go setup using his Hifiman Arya Organics and my Verum one headphones.
The sound quality and detail retreival of the SP3000 is excellent. Remarkable for such a small portable unit. Its user interface is fast and using Qobus as a native app, was a pleasurable experience. This app also allows you to download Qobus tracks onto the internal memory of the device. This DAP also has a slot for an micro-sd card, and it is fast in creating a database for the management of these tracks.The user interface is slick. Plenty of tweeks for sound adjustments, including cross-fade, equalizer and upsampling
I marginally prefered the sound quality of the Hugo2/2go combo but it was very close. As a complete portable unit with a screen the SP3000 shines. An expensive item, but as portables go, probably the current state of the art.