Ken, a range of voltages would turn the sub amp on, and within reason it should be more important to have the voltage high enough. I've noticed that those turn-on triggers are typically referred to as "12 volt"(for example, note this sub amp), and I'd think that the adaptor you bought would be suitable.

By the way, I'll extend the same offer of prayer to resist this Emotiva urge to you that I did to Mark Johnson in the post that you read and commented on.

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Enjoy the music, not the equipment.