I have my ICBM between a Yamaha receiver and a 5 ch power amp.

The slope switch on the sub determines how abruptly, or how gradually, the sub transitions the signal from the other speakers to the sub. The 12 db slope is relatively gradual, and the bass appears to be somewhat overlapped. In the 36 db setting, the transition is more defined, and the bass sounds "tighter", but possibly less musical.

My NHT SubOne has a variable crossover with an 18 db crossover. I found that setting the ICBM to 12 db and the SubOne's 18 db crossover at the same point as the ICBM crossover gives me a smoother blending, as the the SubOne intended. I have not found a problem with the two crossovers interferring.

Try them both and see which you like best.