Will An Attenuator Help Reduce This Hiss?

i've got a little bit of tweeter 'HASSSHHHH' that i'm looking to reduce. as soon as i turn on the amp and preamp it becomes audible. placing the preamp into standby, mute, or on an unused input does nothing to change the level. changing the volume of the preamp does nothing to change the level. the only thing i've found that changes it is fully powering down the preamp - this eliminates it entirely.

i've been advised to insert a line level attenuator (endler, goldenjack, etc) between the amp and preamp at the amp inputs to bleed off some gain and reduce this noise.

will an attenuator reduce the 'HASSSHHHH' sound when reducing the level, or even muting the preamp, does not change things at all?

thanks for any inputs,
Scott