I have mixed and matched for most of the last fifty years. At first because the best in each category was made by a different manufacturer and also a lack of funds to buy what I really wanted.
Much more recently… with adequate funds, simply by upgrading I ended up with nearly all Audio Reseach equipment minus one. My audio dealer brought over the one missing piece without me asking and said just try this. I was sold in a few minutes.
I think the world has changed. There are some high end companies where you get a huge advantage in synergy. Audio Research is definitely one of them. I will not be mixing and matching any more.