I have explained this before but will again. While working for Roland back in 2007 or so selling the V Studio they provided with an amazing multi track recording session. (done on a completely different system.) The tracks are so pristine without a single plugin in sight you can get a fantastic sounding mix. This is master class in mic placement. The band was amazing too BTW.
I mixed this session down on 4 DAW's. Logic, Studio One, Sonar and Pro Tools. I set a mix up with faders and only used a whole number for db settings eg -6db or -8 db etc.. Panning wise I uses only LCR and set all DAW's to C= -3db pan law. I used no plugins anywhere so just basically doing a summing test.
I got a total null with any combination of two mix downs. So there you go. DAW's do not sound different. Oh and BTW I did a blind listening test in a room full of excellent engineers on great speakers and a nice sounding room. No one had any idea what DAW we were listening to.
And for the Mixbus people I am not convinced Mix buss has a sound either. I mixed down a multi track sessions of my son playing drums in both Mixbus and Studio One. However I turned all dynamics and saturation off everywhere and used no EQ or dynamics in Mixbus. Same in Studio One.
Got a perfect null with these two tracks as well. I have stopped using Mixbus now because of this test. What you are hearing is the result of other factors in Mixbus, not the so called sound of the engine itself. It does not have a sound!
Everything else in a DAW however will affect the sound. Plugins, reverbs, time based things you name it. Not the actual summing engine though. Interesting though is the same engineer will arrive at exactly the same sound even if all the other elements in the DAW's are different.