Tube Buffers worth it?

In my experience with the MF, they don't make an improvement so much as change the character of the sound. That's strictly a matter of personal taste. If you want tube sound and an improvement as well, a better (but far more expensive) move would be to upgrade to a tubed preamp.

I guess if someone had edgy solid state gear at the budget end of the spectrum, it might make sense. But in your case, I question the wisdom of sending the signal through yet another device and set of interconnects in search of an "improvement."

The Z Man Tube buffer was better than the MF in my system.Search web for Z Man review.JD

The real purpose of a tube buffer is to match the driving component with a high input impedance and to output a low output impedance to drive long lines, or inputs with lowish input impedances. That's why it's called a "buffer" not a soundtubier. If the output stage on your CD player has a low output impedance, then you really don't need the thing. But sources with weak output stages, and higer output impedances, such as DVD players, cheapers CDs and tuners, can really benefit from such a device.

...But of course, people don't use it for its so-called intended purpose. And in fact, if a solid state device were marketed to perform the same function, it would sell in the single digits.