I have a 2016 Seneca 37HJ and the living room TV (Furrion 39") sound was low volume and sounded terrible. A fairly inexpensive solution I found was installing a Bose Solo 5 below the TV and behind the wooden fascia cover. It fits perfectly and sounds great. Connections are digital audio cord from TV to sound bar and the power supply from the new sound bar was routed up into the electronics cabinet above the TV. The existing 120V receptacle in the electronics compartment is already fed from the inverter so it works on either shore power or inverter. I did drill a hole between the TV cabinet area and the electronics cabinet above it to route the sound bar power cord.
All sound bar remote control functions work great because the grill on the fascia allows the signal to come through, and as another bonus the sound bar pairs with my phone via bluetooth and sounds great! No need to use the crappy dash mounted Jensen and its even worse remote to play music in the living room/kitchen areas.
link to the sound bar info:
https://www.bose.com/en_us/products/...nd-system.html
I love my Seneca but am amazed at some of the crappy equipment specified from Jayco for such a nice coach.