If you plan to use a subwoofer with your pair of Frontier studio monitors, you will need to filter out the low frequency sounds from the input signal to the Frontier loudspeakers. This is so both the subwoofer and Frontier speakers are not playing back the same frequencies, which would greatly exaggerate those frequencies while you mix.
Most professional subwoofers have built in crossovers and filters, so in this scenario, it would be best to have your subwoofer between the signal source and your Frontier loudspeakers in the signal chain.
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