How to best connect active sub to int amp?


This could be a dumb question, but it is bugging me so here it goes:

I have an integrated amp (lfd) which doesn't provide a separate connection for a sub.

What is the best way to connect my sub? If I connect it to the left or right channel, won't it create a different load across l and r channels and thus affect the sound?

I have a NAD C372 with a Paradigm powered sub. The NAD does not have a sub out. Per NAD, the best way is to connect it from the right pre out to the input on the sub. It's been working great for about 6 months now.
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I run my sub via the speaker outs. I only have 2 so I have the main connected via bananas and the sub via bare wire.