Casual PC speakers for music

The speakers should be at ear level; you can put a few shims or something like those under the front of each speaker so they tilt up at your ears.

Room behind is a bit important important; you don't want them right against the wall. give them as much space as you can while still keeping them parallel with your monitor.

Try Ebay for the A2+.  Good details abound.

Check here often:
https://audioengineusa.com/refurbished/

I wouldn't worry too much about the speaker setup. It's not high-end audio. They're on your computer desk. Put them where they fit and sound good and you're done.

"Edifier" R1700s or whatever they're called now are astonishing $150 powered bluetooth or direct connection speakers. Bought a pair for my daughter and was amazed at how good they are when I heard 'em at her place. Supplied with remote, tone controls, and can play loud if need be. 

Put them where they fit and sound good and you're done.

Just like any speaker, they won't sound nearly as good as they can unless you place them properly.  I just went through this.  There's a huge difference that costs virtually nothing.  I adjust the toe of my desktop speakers every now and then just for a slightly different presentation.  It all matters!