Chess may be off the board, Jim, so let me point out that there's very little reason to split a single receiver sub output with a Y-connector and then feed both inputs on the sub. Although feeding two voltages into the sub which are then combined in the sub amp gives you "free" voltage, there's seldom a need for this since most receiver sub outputs are able to deliver more than enough voltage with low distortion. Marc certainly gave you the correct advice. Only if the voltage was too low to keep the sub from shutting itself off should both inputs be used if there's only one receiver output.
