TRL Dude or Joule 150 MKII for Major Pre Upgrade

My CD player is grounded to the chassis by the power cord middle pin. I did hook it up directly to the amp and still get a buzz out of both speakers. I will try the amp in another system tonight to see what happens.
Maybe a power conditioner?

This is *starting* to sound like the preamp is off the hook. Did you make sure a jumper is there between pin 1 and 3 of the XLRs? If that is missing it may not matter what the source is.

A balanced amplifier has 2 inputs: inverting and non-inverting. When you are using the RCA input you are usually using the non-inverting input, which is often the same as pin 2 of the XLR. If you don't install the jumper the unused input can pick up noise.

Granny, can you explain what you meant by "my CD player is grounded to the chassis by the power cord middle pin"? Did you use the multi-meter to measure the chassis and the power cord middle pin and then concluded that?

On the CD player, can you measure the ground of the RCA connector and the power cord middle pin, if you have not done that already? By the "ground" of the RCA connector, I refer to the outside surface area of the RCA connector.

On the power amp, can you also measure the ground of the RCA connector and the power cord middle pin?

Atmasphere, I think it is a system issue. The whole thing worked well previously with the electrostatic speakers. If the only change is the speaker, the only possible cause is the change of grounding.

It is possible that the power supply ground of the speaker is somehow also connected to the speaker terminals. That could cause some amplifiers to be ground-looped. A continuity test between the ground pin of the AC cord and the speaker terminals would sort that out pretty quick.

Atmasphere, my understanding is that Granny is now using a pair of passive speakers. There should not be power supply for it....