Well see how long these two last.
I've got a small update tho. I've been browsing this forum and another one on how to reduce or eliminate the interference. It seems to be internal and related to a tantalum capacitor not being good/powerful enough. What happens is that several data and power lines on the circuitboard run next to audio lines, creating noise and popping. The capacitors are there to reduce these interference.
Earlier this evening I took appart the 1.5" unit to try and find the capacitor. I didn't really know what I was looking for. To make sure the player worked when taken appart I fired it up and played a song. To my disbelief, there was no interference. So it got me thinking... metal case, poorly isolated electronic components... hmmm... What I ended up doing is sticking electric tape to the inside of the case (only on the backside where the electronics would come in contact with it), thus shielding it. I reassembled the unit, took a deep breath, turned it on and played a song.
Nothing, zero, nada. No more interference.
Taking it appart worked for me but I can't say if it will for anybody else. What I can suggest is that you try the player outside it's metal case.
I tried the same thing with the 1.8" player. Unfortunately, it still has massive interference. The metal case doesn't seem to be the problem. Internally, both players are very different.
1.5" (electronic components, circuitboard and LCD screen at the bottom)
1.8" (LCD screen, electronic components and circuitboard at the bottom)
The 1.8 has the LCD resting directly against the chips. It's not the main interference source but it does create a low pitch noise when rested. Once lifted from the chips, the low pitch noise goes away. From the pictures you can also see that the 1.5" makes better use of circuit board space.
1.5"
1.8" (the area under the orange LCD cable is not use for anything)
Right now both players are in the freezer, we'll see if it can help the interference issue on the 1.8" player.