Buying a DAC when you can't try it first

this is a generic "advice please" post.
I'm driving magnepan .7's with a primaluna evo 400 with KT150 tubes.
Most of my music nowadays it tidal streamed via a chromecast audio (CCA) with the optical output going into the DAC of a MusicHall C-DAC (its a CD player with a DAC that can be used by external sources).

I'm planning an upgrade path and leaning toward getting a DAC like the SMSL SU-9 or Cambridge DACMagic Plus and running the CCA optical through the new DAC. But i have no idea if those DAC's or something else at that price is going to improve on the musichall DAC (which some reviews say is a decent DAC).

Or should I ditch the CCA and separate DAC go the streamer route....but I'm worried that tying a streamer and DAC together limits upgrade path. However i am not totally against it. 

I'm just not sure if i even will hear anything measurably better than what I have so thought I'd reach out to you people for your thoughts and experiences. 

....sigh.