the best type and shape of room for audio?

[jandl100]

- In any given rectangular space, fire across the room if you can (i.e. across the short side). This avoids side reflections, which destroy clarity.

Yup, I agree with that.

I've moved home a few times over the years. I've always found in a rectangular room that it sounds best to me when the speakers are against the long wall, firing across the narrower width.
Yes, you do tend to end up in a 'near-field' type of listening, but as Martin says, that's no bad thing as it significantly reduces room reflection effects, ime.

Use room treatment, including your own furnishings.

Mmmm ... depends on the speakers. When I got my omni MBLs I had to take down some absorbing panels behind them as they were definitely spoiling the sound. I still have an absorbent panel behind the listening chair, as this helps a lot with the chair quite close to the rear wall.

Oh, and who said in an earlier post "a room that I can have to myself"? Spot-on, mate!

Yep, I've got me one of those.