Every time you split the signal; you split the voltage. How much voltage each amp gets depends on the impedances the signals, "sees." Every added connection/interconnect will result in a degradation of the signal. You can keep splitting the signal, until there isn't enough left to drive an amp.
"Y" Connector: Can Split A Signal How Many Times?
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Your preamp has pre-outs for amps for two speakers, you use two "Y" connectors to create the ability to connect amps for four speakers.
How many times can you split the signal before it starts to degrade?
.
Your preamp has pre-outs for amps for two speakers, you use two "Y" connectors to create the ability to connect amps for four speakers.
How many times can you split the signal before it starts to degrade?
.