Listening chair height?

Remember yo don’t have to raise your entire speaker... you just have to tilt them or lower your chair. 

OP: 

Sorry for not being so clear.  You were asking about listening on the tweeter axis.  The next larger and closest driver will be a midrang or mid-woofer.  That's what I meant by mid-axis.  I should have typed midrange driver axis.

Best,

Erik

It’s a starting point, and not always true. B&W sound much better on mid axis, I believe that's how they are designed but not 100% sure, and sometimes it just turns out that way after building.

It’s good to listen to the entire range from on-tweet to on-mid axis in terms of height. Usually above the tweeter is a bad area due to crossover issues.

In terms of turning the speakers, some speakers, like Focal, really sound best with little or no toe-in.

Ultimately it is your own ears and room that matter, but I would not attempt to rigidly enforce the on-tweeter-axis rule.