IME, rectifiers make a big difference in sound. I have a box full of various kinds of 5AR4s (including various Mullards) along with two SET amps and a phono stage that use them. Believe me, they do sound different. My fav 5AR4/GZ34 is the Amperex brown base f33 from 1960. They’re often labeled "Made In Holland" but the L in the date code actually designates Brussels. In my all gear, they are similar in sound to Mullards but more open, and just as reliable. YMMV, natch. When I started buying this tube in 1999 it was $58 NOS. Now it’s $200 or so, just like the Blackburn Mullards. Fortunately, I have enough to last until I croak.
I’ll add that a fantastic tube is the KR Audio Riccardo Kron Anniversary Special Edition 5U4G. It can often but not always sub for a 5AR4. In my Allnic phono stage it’s another world, far better than any 5AR4 or 5U4G I’ve tried, including the vaunted Cossor CV575 from the early ’50s.