When it comes to pricing, modified sine inverters are usually a lot cheaper. For example, the Ryobi ONE+ 18V 150-Watt Push Start Power Source at Home Depot is only $80.

As well, some ground fault circuit interrupt (GFCI) devices may not operate properly off of a modified sine wave inverter.

Xantrex has introduced the Freedom Xi, what it calls “a new generation” of advanced true sine-wave inverters specifically engineered for use in all types of mobile applications. The Freedom Xi marks ...

You could save a lot of hassle and loss via inverters that way, although the wire loss might add up. I wonder what voltages a stereo requires.