Apogee Duet -> KRK Rokit Rp5 = Modem-like noise

[jeremyspk]

Hey Softies,
Need some help here.

The problem is as described above on title.

Signal chain:
Apogee Duet ->(Firewire) Mac
Apogee Duet -> Krk Rokit 5 powered monitors L & R

Noise:
It's not hissing, but modem-like humming kind of noise.
Does NOT increase/decrease with output volume.
* All my input volume is 0.

Headphones device:
Headphone out from the apogee duet has no humming noise.

Removal of device:
When the Apogee Duet is unplugged from FIREWIRE, the noise disappear. So perhaps the noise is caused by the Apogee Duet?

Other notes:
My KRK Rokit 5 are powered individually on a 2-pin with 1-hole (CEE 7-7).

Solutions found online:
-> 3prong to 2prong adaptor on the monitors.
For my case, it's already a 2 prong, right? So what, do I re-wire my KRK plugs to 3-pin, then do a 3 to 2 prong adaptor thingy? :|

Btw, I did a rough recording with my headphones yesterday but with KRK off.
No noise encountered (not sure if I overlooked it due to excitement). I go try again to double confirm.

Thank you guys in advance. ~

 

[jeremyspk]

Okay found the problem.
I pulled out the RCA (from another source) and it works fine, noiseless!
It's my RCA in from my PC (on-board sound card).
But weird thing is, it has always been connected without noise, but only starts humming when duet is on. Weird.

 

[blueprintstudios]

that sure is a weird problem but will take note the next time someone asks or if I face such one myself.