Leben CS-300x vs. CS-300xs Mullard vs. Sovtek

Anyone compared the Leben CS-300x (Mullard EL84) to the CS-300xs (Sovtek EL84)? Or know the sound differences between these two tubes in general?
i've heard both but on different systems so a comparison is worthless. i was told that the mullard version comes with some different parts (besides the tubes) but when i asked exactly what those parts were i didn't get a straight answer at In Living Stereo in nyc.
Kublakhan - Thanks. In the meantime, I got the 300x. Suppose I could tube role to find out.
Hey Bigamp,

what is a guy with a username like bigamp doing buying the leben?

Let us know what you think, btw. I love the simplicity of the leben. I'm especially interested in how the headphone jack sounds since I never got a chance to listen to it. I've been told it's excellent.

Actually, maybe you can offer a comparison between it's headphone jack and the Dac-1. I have a fully modified empirical audio dac 1 including the headphone jack mod and it's very nice. i prefer my Stax Omega rig, however.