I'm looking to buy a DMG, but after reading about issues with with LSDJ and it's compatibility with certain CPU revisions I'm pretty worried. Disassembling the DMG to look at chip markings before I buy it is troublesome at best, and the community doesn't seem to have enough info to interpret serial numbers. However, I do have a flash cart, and actually testing the sound channels seems like the easiest and most accurate way to determine if I've got a good CPU.
My question is: What EXACTLY should I do in LSDJ to make sure every function of every channel will work properly? Even better, is there a custom rom designed to help test this?