AMP or Preamp

check out the Aesthetix Mimas intergrated amp hybrid can add DAC Phono or high pass   
Great components 
and I second  Audio Connetion great bunch of guy and sell AESTHETIX

McIntosh C47 pre
McIntosh MC-312

ENJOY!!!

Definitely upgrade amplifier before anything else. You need a high current amplifier cos the Sasha’s impedance dips very low around 80 Hz.  I stand corrected on 80 Hz. 

Lots of good suggestions.  Going to take some time digging into all this.

Upgrade the preamp first. Get the one that is better than the built-in preamp section of your Yamaha receiver. I think your Hegel DAC is probably good not sure I haven’t heard it before. Hegel generally makes good products. If you plan on keep using the Hegel DAC with a Bluesound Note streamer I suggest you look for a pure analog linestage preamp (no DAC). The McIntosh MC2600 preamp has built-in DAC.

Your Rotel RB-1590 power amp is pretty good, and especially for its MSRP of $3k it is really good. I’ve heard this amp before driving the B&W 803 D3 speakers and was very satisfying. Also got plenty of power reserve on tap to drive just about power hungry speakers out there. It drove those B&W 803 D3 with ease and effortlessly. Of course there’s always room for improvements especially to pair with your Wilson Sasha speakers. But for now I would focus on upgrading your preamp and upstream electronics first before the power amp.