LMK how it goes. That would probably determine whether or not I get them at some point. I mostly just do spotify premium.
I am listening off the iphone X right now with the Solaris, and can turn it up about halfway in volume before it gets too loud. I could see myself using it as an daily option as I also primarily use spotify premium. I can spot very minor differences from the Topping NX4. I also do not hear any hiss on the iphone x, and hear a very minor hiss on the low gains settings using the NX4. Although when I try high gain there is definitely a persistent hiss. But I still need more listening time to determine if I will use a portable DAC with the iphone on the go.
I'm sure @davidmolliere will be able to provide a much better comparison as he has the WM1Z. I would definitely be interested in trying out a wifi capable DAP in the future.