In our previous trailer, a 2013 Heartland Trail Runner, it had the standard Jensen AM/FM/CD/DVD player and sounded terrible.
Partly because I discovered the speakers were wired out of phase . . . but also the junk stock speakers.
I put a better pair of speakers in . . . and what a difference!
I pulled those speakers before we traded it in and plan to install them in the new trailer, although I need to get some new speaker grills first.