The Samson M30s are super cheap "monitors". They're quite capable, but I felt like they could be improved.
There is a switch on the back to turn Bass Boost on or off. With the switch in the on position, the bass is significantly over pronounced. With the switch in the off position the sound is tinny and boring. I'd like to change that.
A few screws on the back let's you access the plate amp.
We can see the bass boost switch at the bottom, I traced the circuit as best as I could be bothered to. It looks something like this
It's a high pass filter, with the cut off frequency changing whether C26/C22 is shorted out or not. This cap is a 22nF ceramic type. Replacing it with a larger value significantly improves low end response in the Boost Off setting. Boost On remains unchanged.
I replaced C26/C22 with 100nF and the bass response is much better. I think it's a tiny bit over accentuated, if you are reading this, you should try a 47nF or 82nF instead.
You can solder in 603 ceramics, or through hole ceramics, depending on your comfort level. Using a 603 capacitor results in a much cleaner mod, it might not even be noticeable you voided your warranty!
Capacitances add in parallel, so you don't need to desolder the caps if you use a 47nF in parallel with them.