If your primary concern is sound quality, you can also add a subwoofer to the iRV if it is bass you are looking for. I am sure that the built in amplifier won't handle a big one but just a small efficient one would improve things a lot. Just upgrading the speakers would go a LONG way. They are very crummy. In fact one of my was literally crummy. When I removed it to check the polarity, it was full of saw dust and chips!
Check for clearance before buying speakers. Mine are in the bottom of cabinets and only have about 1.5" of clearance behind them.
For me, the bigger issue is just the function of the unit itself. What a terrible user interface... I don't think you could design something much worse