Crisp sounding tubes for Modwright 5400ES

5AR4 for sure and some Ken Rad VT 231 or some Sylvania's W, found these way more open with airy highs and fabulous soundstage and imaging than the Shuguang.

The Ken Rads are a little better in my system, fuller sounding.

I also have a modwright 5400. Wonderful player. As much as I love the Mullard 5AR4, it would be moving in the wrong direction based on my experience. I would suggest you go with a new production Create Audio tube. I found this tube to be less "tubey" much quieter, and more dynamic than the vintage Mullard. I was very pleasantly surprised by this tube. Finding a new production 5AR4 that is in the same class as the rather scarce vintage Mullards is a huge deal. The dynamics might help out with the overly polite character. When I got this tube in the 5400, the Mullard went into storage. I'm not selling the Mullard, but I haven't felt the urge to put it back in either.
I use Sophia's for 6SN7's. Its the only thing I've tried other than the stock current production Tung-sol's. The sophias are a way better tube, but I'm not sure its the right tube for what you are trying to do.

Brownsfan,

Where can I get these Create tubes?

I wasn't aware that Create made a 5AR4 tube? They have the 6SN7 and the 12AT/AU/AX7's, but I've never seen a 5AR4 by them.

Here is a website that sells them:

http://aloaudio.com/accessories/vacuum-tubes/

Solentgreen, I had the same issue with the Sony. I sold it and bought the modright modded Oppo 95. I like this much better. In my opinion it is more open and extended on top and much tighter in the bass. I tried a lot of tubes with the Sony and ultimately was much happier with the Oppo.