This is how I like to do it - I merge both signals into an amp + cab. Whatever works for you though. Another way would be routing the low side directly to the output as a DI. I just prefer the results I get this way. In this example my crossover frequency is 800 hz. So everything above 800 hz goes to the Darkglass, and everything below 800 hz is clean. You'll also notice that I have a compressor at the front end, and another on only the lows. Both have low ratios. This is in part because I'm not a bass player, so it helps me get more dynamic consistency when tracking. But I presume it's a good idea for most. I use the Level controls in the Darkglass and the Low side Compressor to balance my High and Low signals.