I'm also using the top of the line Herbies Halo Dampers on my CAL Alpha with two 12AX7 C9 Shuguang Tubes, and I'm happy with the combo. I've honestly not noted any drastic differences with the Dampers in place with these tubes, but the differences may be more evident with other tubes?
These particular tubes appeared dead quiet from the get go. I would assume the Dampers should help lessen any possible microphonics. Mark
These particular tubes appeared dead quiet from the get go. I would assume the Dampers should help lessen any possible microphonics. Mark