I am curious what sound card you have, is it a proper add in device, or integral, and specifically what model it is? I would find that information interesting as some folks seem to get this music issue and some do not. And the people I have spoke to that do not get it have real sound cards.
It's an integral. Specifically: Realtek HD Audio 6.0.1.7071
Yay for imaginary hardware!
Augmented Engines granting +2 has the same problem: you want to maximize bonuses, so you use all the speed boosts available to you....
Which is a problem in vanilla. It's an artifical choice (as you mentioned) between making your ships better at fighting and making the game actually enjoyable. There is no choice here, you're going to pick enjoyment/ease of use every time.
Making this ease of use cost more (it should cost nothing, even in vanilla) just further skews the game towards frigates even moreso.
Slow ships are just not fun. The player is already punished with fuel and supply costs from tugs for large ships plus their already prohibitive costs themselves, along with
having to fit silly engine mods to make them even playable at all. They don't need any more dis-incentives.
There's those preference things again....