I've got both versions of the SP and switch between them often (whenever one needs to be charged).

I don't get any interference from using the buttons on either of them.  That sounds really odd.

For what it's worth:  my older model is much more headphone friendly than the newer one.  It has much less high pitched whine and "seems" to be less noisy in general.

EDIT:  forget about output mods, they are a fool's errand

Also do you think prosounding to RCA would bypass this?

I have 3 gameboy advance sps that I use for on the go lsdj work, two of them are model AGS-001 and one is AGS-101.
Now the two 001s have a different type of backlight in them then the 101. Also the 101 has less output to the speaker. It seems to be normal when using the headphone adapter, though.

All of this is fine. The 101 is clearly better because of the backlight. It's brighter and more natural to today's standards.

My problem is that when the 101 is connected to headphones or a mixer it gets clicks and noise whenever you use the buttons. I know not many people use AGSs but has anyone else run into this problem with a model 101.
I need another one to compare it by.