Ive been using the Logitech Z5500 since it came out, it's still working very well, with the only notable difference recently, every time i power on the unit, there is this noise/sound that i cant describe, it's not very loud when the volume on the amp is half way, but as i raise it for some sims, it is quite louder when there is no sound playback.

Also to note is that i have swapped out the audio cables it came with, with Oehlbach cables. (The Oehlbach's have been in use for almost 10 years)

The amp is connected directly to sound blaster ae7 via the 3 jacks.

At night, when it gets very quiet, the sound (when not playing any sound through the speakers) surpasses the PC's total sound output (2 rad's, 2 water pumps, 6 fans).

Any insight, help would be greatly appreciated!