Why do amp A-B switch-boxes have a watt rating?

Probably how much current the internal wiring can handle. 100 Watts into 8 Ohms = about 3.5 Amps of current. The bigger the wire, the more current it can carry.

"The bigger the wire, the more current it can carry."

Right. The same can be said for the switch contacts.

Kal

Thank you Joeylawn & Kr4, I would have to guess that with my 150wpc amp, that since I'm never really blasting the music, that there is probably no real problem since I probably am not putting out over 100 watts at any time.

But then my next question is this: If a certain switch box is then rated at only 100 watts because it basically has thin wire/contacts/circuitboard on the inside, what happens if you then have a 300 watt amp that you are driving very loudly through it?

Studioray, your Odyssey Stratos is rated at 150 watts per channel into 8 ohms. It is usually better not to exceed the power limits of the switch/box otherwise you can damage (burn up) the box's switches. You could probably get by with the 100 watt box as long as you don't demand too much power.

If your gear is good enough why go with box at all?Hook mains into amps posts and use variable out to feed an inexpnsive reciever.That way you won't scre w up sopund of your main sourcve of enjoyment.If it's two pairs of say same inwalls or something switchbox makes sense.
Chazz

"If a certain switch box is then rated at only 100 watts because it basically has thin wire/contacts/circuitboard on the inside, what happens if you then have a 300 watt amp that you are driving very loudly through it?"

I assume you mean that the amp is trying to put more than 100 watts through the switch. If the power exceeds 100 watts only on brief peaks, probably nothing happens. If the power exceeds 100 watts only slightly but for longer periods, say a few seconds or more, probably nothing happens since the switch would typically be rated conservatively. If the power exceeds 100 watts by a lot and lasts for longer periods, then something in the switch will likely melt. When a circuit element is forced to pass more current than its design, it tends to heat up and eventually to melt. This is how fuses work to limit current in a circuit. There may be audible deterioration in the sound quality (briefly) before it melts due to the current limiting aspect of an overheated circuit element. Depending on the circuit element and the extent of over driving, there could be ancillary damage to surrounding elements, including a fire.

Jameswei is correct. However, let me add that inadequately rated wire and contacts will also represent a higher series resistance than larger ones, so you might expect some compromise in performance even if you do not get to meltdown conditions.

Kal

Once again the A'gon team provides a wealth of information and completely answers the question! Thanks all.

Chazz, I guess I was hoping to have at least two of my speaker pairs benefit from the Stratos, but maybe you're right and adding a cheap receiver for the lesser pairs and having the Stratos for the best pair (ATC SCM20SL) is the way to go.