I love my DTR1 and think it sounds wonderful. It is one of several DAPs I have and enjoy while on the go.
Over the course of time i have used many of my DAPs to drive, primarily a variety of iems and, on occasion, full-size headphones, sometimes just out of curiosity. IEMs aside, there have better better and worse pairings with various DAPs and headphones. (It's been a while for many of these, so don't ask about specifics-I simply don't remember). My general assessment, however, is that headphones are best with desktop gear, not DAPs. Some DAPs do better than others, the DTR1 does a very good job driving full-size cans, good enough even for sonically demanind cans that give their best only with the best sounding source gear. But, .... my Luxman P750u does waaaaaay better. Not a fair fight in any sense, size, price, weight, etc., but the truth is the truth. There's a huge difference between 'hey, this sounds pretty good' and 'Holy amaze-balls, I just listened for 3 hours!'
I can enjoy music from a wide range of devices and playback quality levels, and I've walked around me neighborhood a bunch of times, driving Sony 1Z full-size cans with the 'death-ray', and had an awesome listeinng experience. It does a better job with full-size headp[hones than a lot of DAPs that cost way more.