I own a Conrad-Johnson PV-11 that exhibited the ringing issue intermittently. The problem would temporarily go away if I turned the preamp off for a minute and turned it back on. The problem completely disappeared when I added a PS-Audio P-600 power conditioner to my system. Go figure.
Here is a link to an old thread that discusses ringing 12au7's in C-J preamps.
http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1280076126&openfrom&1&4#1
I also use a SS McCormack MAP-1 preamp for home theater which is very nice. It is very clean, detailed, and quieter than the PV-11. If you are looking for that kind of sound take a look at McCormack. I still prefer the PV-11 for music though.
Here is a link to an old thread that discusses ringing 12au7's in C-J preamps.
http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1280076126&openfrom&1&4#1
I also use a SS McCormack MAP-1 preamp for home theater which is very nice. It is very clean, detailed, and quieter than the PV-11. If you are looking for that kind of sound take a look at McCormack. I still prefer the PV-11 for music though.