[Masterrer]

I'm sorry if this is the wrong forum, but I really need some help/advice from the more knowledgeable people.

I have bough a used amp (Pioneer A-400) everything seemed ok at first.
Tried connecting it to the TV to a Lo-Fi stereo system listened to some cds etc.

Then I took it to another room and connected it to my laptop (I'm going to buy a Musiland Monitor 02 or build a y2 for a DAC)

Here the problems began:

When I plug the RCA Jacks into the amp I start hearing this horrible buzzing noise, it's clearly audible and drives me nuts.
It makes no difference if the 3.5mm jack is connected to the laptop or hanging straight in the air.

I have spent this hole afternoon building my own 3.5mm to rca cable (out of a CAT5e UTP cable)

I tested the diy cable, but the buzzing only [size=small]increased[/size], so I plugged the other cable (Loops 1.5m cable with gold plated jacks):
the buzzing was still there,

[size=small]then I plugged the 3.5mm end into my laptop (with the amp turned on) heard a very laud snap crackle pop,
this happens every time I plug/unplug the 3.5" jack, but this time the buzzing was GONE[/size]

I was very surprised and puzzled.
I started listening to music on my laptop enjoying the amazing sound quality compared to my previous setup and after two songs
I heard a medium pop from the speakers and [size=small]the buzzing was back again![/size]

I don't know what is causing it, I can't event keep the amp turned on because of the buzzing it is unbearable,
[size=small]please help me find the source of the problem.[/size]

I have build some simple circuits and fix computers for a living but this confused the hell out of me...

 

[Paul J.]

What happens when you jiggle and mess with the rca plugs while they are plugged into the amp? It sounds to me like it could be a loose/dirty connection or a mechanical problem with the jacks. Is the problem still there if you use a different set of inputs?

A pop when plugging or unplugging isn't unusual, BTW. It is generally advisable to have a different input selected when you are connecting or disconnecting a cable.

Paul