No difference, because ultimately its the levels you set on the sub that determine its output. Connecting to the amp does not affect the amp at all. Only real difference is a practical one- which wires, how long, and where they go. In terms of sound the end result is all the same.
subwoofer connection
I have read about an alternate connection for subwoofers. The alternative is to bypass the A/V processor and connect the subwoofer to the output from amplifier. In my case I have MX 122 Mcintosh A/V processor with two sub out connections, RCA or XLR. Instead of using the sub out of the processor, connect the sub to one of the front channel mono block amps in this case a Mcintosh 611. Would this improve bass response and would I have to go into the bass settings of the processor to increase the low frequency range of the amp and change any additional settings for subwoofer connections. Any thoughts would be appreciated.