While I agree that DAC, CD, vs TT/PS is pretty irrelevant. All can be optimized for the speakers… often that is good. But…
If you are looking at even mid priced speakers. They should hook up anything that they have in the store that you want. I recently went through an evaluation of some equipment. In this case it was integrated amps. I chose the speakers (75 pounds each) which they had to swapped in. Then we chose the DAC and streamer, then they swapped in the 75 pound amps… three of them in turn. Then we went back to what we thought was the best sounding amp.
No sale resulted… for a couple months. Then he bought better separates from the store.
So, I guess unless it is Best Buy they should allow you to choose the components.