Anybody know what happened at JOB...

abery, I have to disagree with you, my friend. You had the Rogue pre, prior to your BHK, and you needed to do the same with the Schiit passive. The problem is not with the Nuforce and Zu interface, but the pre’s and the Nuforce. If you eliminate the pre’s, and go passive, without signal playing, turning the passive volume up to max, you would not get hiss or hum ( if no grounding / wiring issues ). It is fine if you want to change the amp, but I remember mentioning a long time ago, the Nuforce, and Job 225, were designed to be driven passively. My Luminous passive ( awesome ), at max volume, without music playing ( dac is on ) shows zero hiss, or hum, through my more efficient speakers, when using the Nuforce. But I understand how much you enjoy tube preamps, so the Nuforce is not a good match, interfacing with your preamps.

adameos, in your 1st room, when you experienced the hum, might be because of a severe ground loop, or even a light dimmer, on the same circuit. Could be any number of things. But the amp is quiet, when used with better matched components, preceding it, in the audio chain.

For what it's worth,I had a STA200 with a Rogue tubed pre and it was dead quiet.But I do have a dedicated line and no dimmers in the house at all.I do have a friend with dimmers that cause hum unless they are turned off even though they don't share a circiut.

jtcf, + 1

abery, I have to disagree with you, my friend. You had the Rogue pre, prior to your BHK, and you needed to do the same with the Schiit passive. The problem is not with the Nuforce and Zu interface, but the pre’s and the Nuforce. If you eliminate the pre’s, and go passive, without signal playing, turning the passive volume up to max, you would not get hiss or hum ( if no grounding / wiring issues ). It is fine if you want to change the amp, but I remember mentioning a long time ago, the Nuforce, and Job 225, were designed to be driven passively. My Luminous passive ( awesome ), at max volume, without music playing ( dac is on ) shows zero hiss, or hum, through my more efficient speakers, when using the Nuforce. But I understand how much you enjoy tube preamps, so the Nuforce is not a good match, interfacing with your preamps.

You are correct. I should have stated for my current system. The amp is dead quiet with a SS pre. One thing between the RP-5 vs the BHK, the Rogue was a tad more noisy in the tube hiss, noise department. With the BHK, I could have actually lived with no passive if my listening position was just a little farther back. Probably just two different pre amp designs or output gain.