[hueslema10]

Dear NuPrime Owner,

I have purchased the combo PRA-9X and the STA-9X. This combo sounds superb. Unfortunately, I have discovered that the preamplifier produces an audible hissing noise, and even when the preamplifier is switched off, some noise remains audible. It almost seems as if the preamp has a leak. Maybe it is supposed to be this way, but this is the first time I've encountered this issue. Since it was an investment for me, I would like to be sure that I do not own a faulty device.

The power amp is quiet when all inputs are disconnected, and the device is positioned at a large distance from other devices. The power connection is from another room. The noise remains consistent and does not get louder when I turn up the volume. I use Klipsch Heresy speakers, and as a horn system, they are super sensitive to such behavior. However, with my previous amplifier, which was of lower quality, I never experienced this issue.

What is your experience with this? Many thanks.

[seikosha]

Do you hear the noise when the preamp is unplugged?

[hueslema10]

There is no noise when the preamp is unplugged. The power amp is quiet. The noise disappears when I press the mute button.
Perhaps it is normal behavior, and it's the trade-off for achieving good sound

[rustydoglim]

Whenever anyone mentions noise, please help to quantify the problem.
1. Where did the noise come from? typically it is from tweeter.
2. What's the efficiency of the speaker?
3. How far away did you hear the noise?
4. Did you try to cut off the ground with a "cheater plug" to test if there is any ground loop problem?

[hueslema10]

Dear seikosha and rustydoglim
Thank you very much for your inquiry

-The speaker is a Klipsch Heresy 3 with more than 95 db
-The noise comes from the middle horn as well from the tweeter. ( More from the middle horn )
-At 1.5 meters, I can still perceive it faintly
-The idea of using the cable without grounding is something I need to try out. Thanks for this hint
 I always thought that a problem with grounding causes a humming sound not a hiss