Improve sound

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.

For that budget I’d upgrade the DAC, and for God’s sake lose the optical digital connection. Get these two things and I think you’ll realize a notable improvement.
https://www.amazon.com/dp/B096S6HBQY/ref=syn_sd_onsite_desktop_30?ie=UTF8&psc=1&pd_rd_plhdr=t

https://www.usaudiomart.com/details/649932466-acoustic-zen-mc2-digital-coax-cable-1m/

Here’s a review of the Draco DAC that, as it turns out, is pretty comparable to my $1100 Musician Pegasus DAC that is, in turn, pretty comparable to the Denafrips Pontus ll. DO NOT underestimate the role of the digital cable because it makes a huge difference.
https://soundnews.net/sources/dacs/musician-audio-draco-r-2r-ladder-dac-review/

My advice, your next move, if 2-channel audio is important, is to invest in a good stereo integrated amp that’ll obliterate your AVR.  Use the front L/R preouts from the Anthem into a good stereo integrated and it’ll be a HUGE improvement.  AVR amps and preamp sections by and large suck as they’re designed to cram as many features into a box at a palatable price point.  The first casualty — power supplies.  Why?  Because they’re one of the most expensive components in good audio equipment and not even Anthem can include quality power supplies and keep their AVRs cost competitive.  So, my advice, do the DAC now and if 2-channel is important your next upgrade fer sure should be adding a good stereo integrated into your setup. 
Anyway, hope this helps, and best of luck.