Hum/Buz fro JC1

houstonreef, I had the same exact strange behavior with my A21/P3 setup. I could never figure out what the issue was. I know this does not help but I eventually got rid of my Halo gear. I wonder if this is some sort of design issue with the Halo products?

The pre is connected to PS audio Dac. I had disconnected the ground wire on the power cord of the pre but the problem is till there. Downunder and Seadogs1, can you explain to me how to do it.

Thanks

Houstonreef, have you tried what I recommended?

Audpgile, there is no tv near by. there is one cable jack right behind the componet rack but the cable jack does not connect to anything. Audphile1 what do you recommend me to do with this cable jack?

Do nothing with the cable jack. You may still want to try disconnecting the coax cable at its first entry. If you have a ground loop that causes this humming, you will know it when you take out that cable. Your amp may not be sensitive to this ground loop, but your preamp may be, since you say the noise is gone when you disconnect the preamp from amp. Try it, if it's not a big deal. Other than that, it could be your preamp that's causing this problem. Tubes, other things......who knows. Also try a cheater plug as recommended above.