At home I have a 9.1 AV system (Samsung / Yamaha / Axiom Audio)
In trailer I use the TV speakers. I don't use the trailer speakers, either inside or outside.
If you need better sound in the trailer you could add a soundbar. These come in many different quality/price points. Use the audio output from your TV.
2013 Jayco WhiteHawk 27DSRL, 2012 Tundra 5.7 DC
1996 Honda 750 Nighthawk
Location: Columbia SC