Usually, car audio systems like CD player or cassette player have good audio amplifiers, with four channels (front L/R and rear L/R) of enough power for in home use. The radio tuner is also of high quality, with automatic best frequency selection and RDS information. Not all car audio systems have audio auxiliary inputs, although with a little tweaking, you can add audio line level inputs to a cassette player so you can use it as audio amplifier with any audio source.
There are plenty of how-to's about this subject. Yet I couldn't find one that handles the memory loss problem. Car audios are designed to be continuously powered by the battery. Therefore, most don't have a permanent storage memory for settings. Upon disconnecting the power, the device loses all audio settings and stored radio stations. This article will deal with the memory loss problem. Unless you will never unplug the DC adapter from the mains, you will need some kind of battery backup system. There are two approaches here: find and power only the CPU from battery or power the entire device from battery.
Car audio powered in home