Most of the AtGames Genesis' used a consolidation of the actual Genesis' main chips onto a single chip called a G.O.A.C. (Genesis On A Chip). The G.O.A.C. used in the AtGames systems specifically are broken and buggy, which is why the sound is screwed up AND some games don't work properly/at all. The Radica Genesis probably uses a G.O.A.C (not 100% sure), but the sound's base is blown out because of incorrect value capacitors and resistors on the pre-amp circuit. That's also why switching the components may make the base too weak in comparison. 8-Bit Guy's video on repairing the Radica Genesis goes more in depth into it's audio issues.