Those sample files you have are for much older MAME versions that didn't support analog sound emulation for Donkey Kong and Donkey Kong Junior. They're not usable in 0.152, as that was released long after analog sound emulation support was implemented. It's not possible for the end user to make the sounds more accurate to that of the PCB. You'll either have to use an older MAME version + the old sample files, or you'll have to settle for the inaccurate analog sounds of newer MAME versions.