Improve sound

I like the Martin Logans. I think a tube DAC might give them real warm and liquid sound. MHDT Orchid comes to mind.

Although your speakers have a fairly high sensitivity specification, they are a 4 ohm impedance load. Your amp does not provide a spec into a 4 ohm load. My guess is an amp is needed that likes a 4 ohm load or find a speaker with 8 ohm impedance. 

+1 to the Orchid DAC or a Denafrips  or Pure Audio. The SQ of the Cambridge is OK but the app is rubbish.

Rubbish! Love that word and had to use it.

Actually Fuzzy gave you the first move.

Find a used Ares 2 Denafrips Dac-no tube,

or a Black Ice DAC-Has tube and some hum 

to go with it. The AMT tweeter with a so-so

amp might dictate a tube for softening.

Keep us posted!

DAC!! Blusound dac is not even on par with an ifi hip dac 2. You can sell your blusound and par with your cash and buy the Gustard R26. You will be blown away.