Proper way to play audio with an Arduino

I've been prototyping a speaker box thing that plays a sound once the Arduino is powered. The circuit right now looks like this.

I'm not sure if there are any improvements that could be made to make it safer to drive the speaker or make the sound quality better. The audio is directly loaded onto the board and uses the PCM library to play the audio and whatnot. Do I need to add an amplifier IC somewhere? Would adding SD card capabilities increase the sound quality? The current circuit uses an old 3W 4-ohm speaker but I am thinking about picking up an 8-ohm 1W speaker for a smaller package, not fully sure how that will change things exactly.

“play sound” is a bit broad. What sound do you want to play? Beeps and Buzzes or an orchestral rendition?

Beeps and buzzes is well within the Arduino capability. Even understandable speech. Any higher quality requires more hardware or a more capable computer, like the Raspberry Pi.

SteveMann:
"play sound" is a bit broad. What sound do you want to play? Beeps and Buzzes or an orchestral rendition?

Beeps and buzzes is well within the Arduino capability. Even understandable speech. Any higher quality requires more hardware or a more capable computer, like the Raspberry Pi.

To be specific, its a sound file of a text to speech (Japanese) that has been converted to a mono, 16 bit, 8000hz audio file which then gets converted into the PCM stuff. So I guess it does fall under the "understandable speech."