Preamp Noise with High-Efficiency Speakers

As you know, the noise issue becomes hypercritical when you have very high efficiency speakers.

Make sure no power cables are touching each other or any other cables. Cross at right angles with a few inches of space in between.

Usually it would be the input interconnects from source to preamp. You could probably test that by switching to a shorted unused input and seeing if the noise persists. Also make sure the shielding in the cables is oriented in the right direction. When in doubt, reverse them. (Make sure your cables are shielded.)

Get the cables up off the carpet if you have carpeting.

While it probably is the very high efficiency of your speakers there are pre-amps with low enough noise levels to make them silent, especially SS ones. What I suspect your problem might be is that the pre-amp has too much gain for your amp which has a high sensitivity. Most pre-amps typically have gain from 10db to 26db which may be too much. A pre-amp with zero gain might be the answer. With digital sources you really do not need added gain from your pre-amp (but this does not negate the other values of using a pre-amp). Think Placette or Wyred active units. Or, if you can deal with a cheap add-on resolution, insert a Rothwell fixed attenuator between the amp and pre-amp.

A remote possibility, easily to check, is a 60 cycle hum. Simply terminate the PC from your pre-amp with a cheater plug and see if it goes away. If it does you have sourced your problem if not your solution.

Hope that helps a bit.

Newbee nailed it. Nice post Newbee.