Best power amplification for simple tones with a speaker?

I’m using an Arduino Nano in a project with a power source of 5V, and I want to simply play a tone as loud as possible using the tone function in the IDE with my 2W 8 Ohm speaker. I’ve tried the simple transistor set up that I found on another thread here (image attached to this post), and an LM386 audio amplifier circuit using an LM386N-1. The volume that I achieve with these two set ups is basically the same, and not as loud as I would like.

Is there a different transistor set up, or another simple circuit that I can put together that will give me the most power/volume? Apparently these speakers can get quite loud - I’m just a bit stuck with what to try next.

PAM8403 board drives its load bridged, so will provide 4 times the power.

As I understand it, that amp is for stereo output and I'm only wanting to drive one speaker with a tone, so mono. Can I use something like that still?

Sure. You can leave one channel unused. Or, add another speaker (and connect the inputs together) to double the power again (+3dB).

And/or, a 4-Ohm speaker will also give you twice the power as an 8-Ohm speaker (double the current at the same voltage). ...But that doesn't necessarily mean it will be louder because some speakers are more efficient than others.

mangojack:
As I understand it, that amp is for stereo output and I'm only wanting to drive one speaker with a tone, so mono. Can I use something like that still?

Yes, one is a smaller number than two so its possible.