The SS4 doesn´t have a common loop, unless there are several versions. It has a line-out tap for slaving or WDW rigs, as far as I can remember. There are several newer units that have a common loop for more typical current rigs. This can easily be replicated with just about any good MIDI switcher and a bit of cabling and programming, but that´s obviously adding more gear.
As for the question here, the SS4 has a small load on the unused amps which probably can handle a bit of normal delay without burning up. Same as all the quality alternatives, I don´t think anyone would go to the expense and trouble of having full 100W loads on what´s supposed to be silent amps. There´s also the fact that output transformers are much sturdier than you might think. But in the end you´d have to ask Bruce, and I suspect he wouldn´t be so keen on endorsing something it wasn´t intended for.