Of my four AMP cards this has definitely the nicest sound overall, but there are issues, first of which is very audible and persistent static with the current firmware when Wi-Fi is on, which means using the DAP to stream music or watch movies is unpleasant at best, but basically untenable. Of much less concern is the momentary ringing you can get from the tubes with any kind of sharp movement or impact, even plugging in headphones or setting the DAP down.
Speaking of headphones I have done all my listening to date with IEMs, so the limited power output of the AMP13 has not been an issue for me at all; it’s worth keeping in mind if you prefer a set of hard to drive cans, however.
Is the wonderfully liquid, articulate, warm & luscious sound of the AMP13 worth sacrificing the streaming possibilities of the DAP? For me yes, but it is a major disappointment.