For your Wilson Sasha DAW speakers you might want to stretch your budget more than $20k for both preamp & power amp(s). Additionally, you will also need to purchase front end source component(s) whether digital or analog front end source component(s) or both.
The Wilson Sasha Daw are very fine speakers and you will want to feed them with highest fidelity signals from electronics.
Wilson speakers, especially their higher end series such as the Sasha Daw, Alexia ll, Alexx & Wamm will pair really well with D’Agostino, Audio Research (ARC) Reference series, VTL, T&A, Pass Labs (higher end models) & higher end Naim 500 series separates among others.
For your Sasha Daw I would look into ARC Reference series gears or D’Agostino Progression series or Momentum series if you could afford them. Try to look for used ones either here on Agon or some other sites.
I was going to recommend the following Naim 500 series separate gears to you but figured will be way way over your budget but you will get the best out of your Sasha Daw speakers. The following Naim 500 series separate gears are as follow : Naim NAP 500 DR power amp + Naim 555 PS DR power supply unit; Naim NAC 552 linestage analog preamp + Naim 555 PS DR power supply unit; Naim ND 555 digital streamer/DAC + one or two 555 PS DR power supply unit(s), one 555 PS DR feeds power to the ND 555 digital side of thing and the other 555 PS DR feeds power to the ND 555 analog audio stages or you can just use a single 555 PS DR power supply for the ND 555 streamer/DAC. Assuming you are going digital audio source. If you aren’t into digital front end sources then go look for a great turntable with its accompanying accessories eg tonearm, cartridge & phonostage pre.
However, these Naim 500 series separate gears will run you around $100k altogether, for the digital streamer/DAC, analog linestage preamp & power amp together with their 555 PS DR power supply units, one for each of all those three components. But the sound is magical highly musical and very musically engaging and involving. If you decide to go with these Naim separates I highly recommend you use their DIN connections (interconnect cables) to connect between these Naim components as they will sound better than using their RCA single-ended connections. Naim’s DIN proprietary connections are basically their XLR balanced connections version.