The sound you describe may be attributed to inproper grounding of your amplifier or a faulty audio cable used between the AirPort Express and the amp. Are you using the analog or optical digital output of the Express for your amp?
Do you have the Express connected directly to a wall outlet or to a power strip? If a power strip are there other transformers/adapters connected to the same strip?
Thanks for you reaction.
I've tried the amplifier connected to a grounded wall outlet, with the same result.
The audio cable connected directly to my ipod gives a good result, so I think the cable shouldn't give the problem.
I use a analog connection, not the digital optical output.
The Express was connected directly to the wall outlet, no other adapters are there.
I've tried to connect the Express with an external power cable to see if a different place would give a different result, but no.
Thinking of the differences between the connection of the Express to the amplifier and a laptop or ipod to the amplifier is the connection of the Express with a cable to the wall outlet. So some kind of ground-problem could be the case.
But since I don't know how to solve this problem, I still hope that you have more/other suggestions to solve this.
If, for any reason, the base station's internal DAC or audio circuitry was bad, I would have expected that the noise that you are getting on the amplifier would be heard on any device connected to the base station. However, it may just be possible that your amplifier has a more sensitive input and why it does show up there.
I assume that you have already tried other audio inputs (not phono) to see if this is not just related to the AUX ports that you are using now?
That would depend on your audio streaming source I would think. I am assuming that you are using iTunes on a Mac or PC as that source ... correct?
If so, you may want to set the followng options in iTunes:
- iTunes > Preferences > Playback > Deselect "Crossfade Songs," "Sound Enhancer," and "Sound Check."
- iTunes > Window > Equalizer > Deselect the "On" option.
Thanks again for the hints and tips for the 'rumble' problem.
I've tried the new options you suggested. But still no progress.
The 'rumble' is already there when I connect the Express to the amplifier.
Even before I start the music.
Since all other equipment is working fine on the AUX-port and the same cable, I blame the Express for the problem. Therefore I go back to Apple with the Express.