Modwright Oppo 105 - Upgrade Power Supply Tubes?

Thanks to the forum & a post by Mrtennis I upgraded the 6sn7 tubes to 1950's RCAs and am most pleased with the change in sound. In my 2 systems with my 2 ears the player went from digital sterile to nice and musical. I am not a fan of the supplied electro-harmonix 6SN7 that is supplied. Thanks again Mrtennis. And here is my question, has anyone found it beneficial to upgrade any of the tubes in the power supply?

Many thanks.
I have used Both the Phillips 5R4GYS and the Sovtech and the Mullard 5AR4..The Mullard is the one to go with.You see in a 5R4GYS vs 5AR4 , the plates are too close together in the phillips and while this tube will is not a good match for the Modwright 5AR4 driven power supply. Find yourself a good REAL Mullard for around $120. You don't need to run a $350 metal base. This tube will tighten the bass and give everything a little more weight.The phillips sounds bloated and blurry in the low regions.
When I had the MW Transporter, Tung Sol NOS 5u4gb was by far the best rectifier tube. It was musical, bloom, detail ... JJ GZ34 for $18 was also excellent and definitely worth a roll.

For reference, I found Mullard GZ34 too warm and rich for my taste.
An extremely musical combination that I am now using (in my Modwright Oppo-95) is a pair of shorty, chrome dome Sylvania 6SN7Gs (w/ black base, green lettering), and an RCA 5R4GY. Very natural sounding across the board, with a great soundstage, and awesome mids. Nothing seems missing in this pairing.

Sorry, I don't agree with the above statement that a 5R4GY is not a good tube match for the Modwright PS9 power supply!
Black Treasure CV181-T was the BEST signal tube in my MW Transporter. I found Sophia 6SN7 to lean for my taste.
Agree completely with mattmiller.  The Philips 5R4GYS has nothing on the low end on the Oppo.  I spent a year diagnosing what was wrong with my system.  I had never even tried the stock tube supplied by Dan.  I was ready to sell everything off in frustration when I made a last ditch effort and changed out this tube. Magic.  Try for yourself and see.