Hey Tom! I told you it was good! So far for my system the Ken Rad Black Glass VT-231's are the ultimate in weight body, and seductive sound. The Sylvania Metal Base 6SN7W's are super good! But... they're hard to find with low microphonics.
The Tung Sol 5881's give a lot of dimension and front to back soundstage layering. Nice effect. Plus they are fractionally more detailed than the Sovteks. But until the TS 5881's are broken in, the Sovteks will sound a bit better.
As for the Mullard 5AR4 - I'm using a GZ32 and I don't know if it's all that much better than the stock Philips rectifier tube.
The Tung Sol 5881's give a lot of dimension and front to back soundstage layering. Nice effect. Plus they are fractionally more detailed than the Sovteks. But until the TS 5881's are broken in, the Sovteks will sound a bit better.
As for the Mullard 5AR4 - I'm using a GZ32 and I don't know if it's all that much better than the stock Philips rectifier tube.