I found that using adaptors like an RCA to 1/4" was really bad. I may have had bad ones but I was surprised by this. Get a cable that RCA on one end and 1/4" on the other. This will help.

It is really pretty quiet. I would describe the noise I'm getting as similar to the hiss you hear from compression drivers. It's not as loud as that though. and you certainly cant hear this unless your head is in the speaker. This could also be something related to my system.

hope this helps,

Bill