15" is deep enough

I would be a little more lenient, say 18 inches. Though I get the point you are making,.
As far as being the benevolent despot goes, I would make it illegal for cable manufacturers to make a speaker or interconnect cable that cannot bend less than a 3 inch radius. (I'm looking at you Transparent!).

I've been there. So, I built my "final" rack, and made sure that the bottom shelf was 22" deep to handle those mono blocks that I would someday possess. Well, my "final" mono blocks turned out to be 15" deep. - LOL
Kenny

Good luck with that one.

All is good!

How would your (well-intentioned) law apply to horns I wonder?

Chrono:

I excluded speakers. :) I am a despot, but not crazy. :)

Well then, you get my vote ...

Subject- 15" is deep enough....! 

And that's what my partner said on the first night...............when she had a look at my equipment...........................while leaning on the audio shelf! Mwahahahaha

Sorry, I just couldn't help myself.

Now I really feel inadequate,
shelf wise.

It's not the size of the shelf,  it's what's on it !!!!!!!

Can I turn my amp sideways to avoid prosecution? 

Sheesh! About 12-13 years ago our amps were a design that was about 28" deep.

Dealers didn't like them as they didn't sit on shelves well, which really isn't where they were intended to sit.

Apparently a lot of people liked the look, so much that we've gotten orders for amps built that way now (google Atma-Sphere Silver Edition for an example).

@sbank only if they say McIntosh on the side. :)

Over 9" is already too deep technically LOL!

Schoenberg is too deep for me. 

I personally think amps should sit on the floor between the speakers and like them to be deep and narrow.