I run a couple of Sonic Frontiers SFS 40's, and was wondering what the thoughts are on running Halo's on the power tubes? I have tube coolers on them now, and have noticed no problems with ringing or microphoning. (not to say that it isn't happening) Anybody tried the Halo's? Think it's better to use them as opposed to coolers?
In general it is far more important to put dampers on the small-signal tubes (preamp and input tubes). Power tube microphony is much less of an issue. Probably best to stick with just coolers on the power tubes.
I have Hal-o's on 300B's in Manley Retros. They make a nice improvement in bass, clarity, and spacial characteristics. I have never tried coolers. You can send Hal-o's back for a refund if they are not worthwile in your system.