For Jh2os--there is never too much of a good thing when it comes to tubes!!! :^) I use an Audio Logic DAC, a Jadis JP200 preamp and a pair of Lamm ML 1.1s with no problems, but I do note that the better tubed units and solid state units are sounding far closer to each other these days than they did 15 years ago. I imagine if you get some heavily colored tubed components they may overdo it in terms of fidelity to the signal, but on the other hand you still might like what you're hearing enough not to care.
Mdp0430: Probably yes to some extent with the preamp, particularly if you've got a good CDP. With something like the MF X10, depends on your objective, in my opinion. With the MF you're adding more circuitry into the signal path, and essentially coloring the sound. In that case, if your objective is fidelity to what's on the CD, unlikely unless you really have a poor solid state CDP. But if your objective is to tailor a sound from CD that you can enjoy musically (and I know a lot of people who have a hard time doing that), and the MF does that for you, then that's probably the ticket.
Mdp0430: Probably yes to some extent with the preamp, particularly if you've got a good CDP. With something like the MF X10, depends on your objective, in my opinion. With the MF you're adding more circuitry into the signal path, and essentially coloring the sound. In that case, if your objective is fidelity to what's on the CD, unlikely unless you really have a poor solid state CDP. But if your objective is to tailor a sound from CD that you can enjoy musically (and I know a lot of people who have a hard time doing that), and the MF does that for you, then that's probably the ticket.