I'm kind of loathed to going in and changing the volumes of instruments and the song itself because I would like to use songs supplied by Miker (as-is with how they are supplied). And I want to leave myself open to the option of having lots of different songs (I currently have 2) depending on disk space. I don't want to change all instruments in all songs if I can help it. I'd rather run them through code which limits volume instead.
Ah you haven't quit understood how it works. Let me help you. You write an email to Miker and tell HIM to lower the volume of all instruments
Seriously, I haven't thought about this till now, and it turned out quit Ok. But now I will tell my OSon to use lower volume Instruments from the start.
Haven't checked how the RMT replay does the lower volume, however, doing it manually before hand is the best option, I think.
What you should not forget: There is more then just the volume. A high pitch will be more recognizable then a lower pitched melody instruments.
Finally, music instruments use probably a volume envelope, so they are not always at level 15. And an explosion or pick-up of an item has a fast attack and can be very well recognizable when played. Additionally, the player has some expectation that he hears a sound when he picks up or does something. So he hears the sfx pretty easily.
Keep in mind, that there is some kind of limit in POKEY. Something along the lines that the added volume of all channels shouldn't be higher then 30 or so. Should be in the ABBUC-SW-Contest tips and tricks sheet. So, lowering the instruments is a good idea anyhow