Switching between two receivers — one set of speakers

Yes, you can absolutely set up a system to switch between your two receivers (Yamaha R-2000 and Nikko 1219) while using the same pair of KEF Q500 main speakers and your Klipsch 12" subwoofer, without having to re-wire everything each time

Here's how you can achieve this:

1. Main Speakers:

• Speaker Selector Switch: You'll need a speaker selector switch designed to handle two amplifiers and one pair of speakers.
• Connection: Connect the speaker outputs of both your Yamaha R-2000 and Nikko 1219 to the input terminals of the speaker selector switch. Then, connect your KEF Q500 speakers to the output terminals of the switch.
• How it works: The selector switch will allow you to choose which receiver's output goes to the speakers at any given time. You should only have one receiver powered on and selected at a time to avoid damaging your equipment. 

2. Subwoofer:

• Subwoofer Line-Level Inputs: Since your Klipsch subwoofer is currently fed via the pre-out of one receiver, you'll need to check if your subwoofer has line-level inputs (usually RCA jacks).
• Simultaneous Connection (if possible): If your subwoofer has two pairs of line-level inputs (like some JL Audio models), you might be able to connect the pre-outs from both receivers to the subwoofer simultaneously. The subwoofer would then handle summing the signals to mono. However, be sure to only have one receiver playing audio to the subwoofer at a time to ensure optimal sound quality.
• Switching for Subwoofer: If your subwoofer doesn't have sufficient inputs for simultaneous connection, you can use an audio AB switch for the subwoofer line-level connections, switching between the pre-outs of each receiver to the subwoofer's input. You'll connect the subwoofer outputs from both receivers to the "in" jacks of the switch and the subwoofer's input to the "out" jack. 

Important Notes:

• Overload Protection: When selecting a speaker selector switch, ensure it includes impedance matching and overload protection to safeguard your receivers and speakers.
• Power Ratings: Pay close attention to the power handling specifications of the speaker selector switch to ensure it can handle the power output of your receivers.
• Tube Amplifiers: If using tube amplifiers, it's crucial to put them in standby or turn them off when switching to avoid potential issues.
• Volume Matching: When using one subwoofer with two systems, you'll need to carefully match the subwoofer's volume and crossover settings to each receiver for optimal sound integration. 

By utilizing a speaker selector switch for your main speakers and either simultaneous connection (if your subwoofer supports it) or an audio AB switch for your subwoofer, you can easily switch between your two receivers without any re-wiring hassle.