Outboard Dac for Bluesound Nano

Looks like you are doing a great job of building on your speakers and amp as a base. To get each component of similar caliber and fidelity I would recommend finding a used Schiit Yggdrasil (1st choice),  Holo Audio, or Denafrips or new if you can save up. You want to reach as high as you can. Then after recovering financially you can replace the Bluesound streamer with a more capable one... and it is likely you will have a very well balanced capable system., 

Not sure why no one talks about Pegasus II here. But check out the reviews. 

I just added a LTA Aero to my Blusound Vault. Well, I ordered it, should be here in a few days.

What specific improvements/sound characteristics are you looking for?  Are you open to buying used?

I'm no dedicated DAC expert. As a matter of fact I have only owned one. But...

I do have a BlueSound Node (N130) which is basically the same streamer section you have. I upgraded the Node with an LHY LPS.

I use a Black Ice Tube DAC $899  and I love it. You'll need some nice NOS tubes to make the DAC shine. (DAC is sold out atm, so perhaps this is all moot unless you are not in a rush)

Add a DH Labs USB cable and later add a Teddy Pardo power supply (LHY doesn't seen to have one for Nano yet).

I compare this to an analogue source at more than 10x the cost and it is very satisfying, exclusively streaming, via Qobuz and SXM.