Metal-base and non metal-base 5AR4/GZ34?


Sonically, what's the difference between the metal-base and non metal-base 5AR4/GZ34 rectifier tubes, Philips/Amperex or Mullard? Especially as they perform in the Modwright 9.0 SE preamp?
pmboyd
Anyone have any thoughts on the Mullard GZ34?

http://www.dougstubes.com/rectifiers/5ar4-gz34/mullard-gz-34.html

I think this one is the non-metal base one.