Sub Integration

Thanks Bruce,
You've offered some very good suggestions. A couple more questions that maybe you and others can weigh in on......
The PSB Imagine B speakers are rear ported and PSB suggests that the closer the speakers are placed against the rear wall the more enforcement there is in bass. Mine are placed about 3 feet away from the wall. PSB offers port plugs for some of their floor stander models but not for these. I have considered plugging the ports and port plugs are offered in a generic sense on the Internet but I wouldn't know which and what size to order. For an initial experiment on the results of plugging the ports with the design you suggest, I have an abundance of foam of different sizes, much like sealing up openings around a window air conditioner (soft foam). Compressed and sealing up the ports, would that suffice for an interim port plug?
The Outlaw ICBM that I use for bass management recommends to set the crossover frequency on the subs to their highest frequency and then let the ICBM determine what frequency the subs actually see. Does that make sense?
The NAD amp and the PSB speakers sound very good. I originally had the speakers connected to a very good HK receiver. The sound was horrible. Like many have said that there is some truth to NAD and PSB having some chemistry since they are, or were, sister companies.
So far I have received some great advice from you and others. Will continue to obtain sound that is as good as my system is capable of.
Thanks All

The 1/3 rule suggested by rbstehno is appreciated but does not apply to my listening space. My room is 15' wide and 20' long. If I apply the 1/3 rule then my listening point would be only 8' away from the speakers and in the way of casual traffic in the room. Not practical for my space. I really appreciate all of the suggestions offered and will continue to experiment with all of them. Perhaps I have a very challenging task.
Thanks

yogiboy suggests that sealed and not ported subs are better for music and ported are better for for HT. My aim is for music. I have read opinions from others that this is true. Originally I had one sealed Klipsch sub. The second sub I added is also a 10" Klipsch sub but is front ported. If I plugged the port on the second sub would I have, in effect, two sealed subs? If so, what plugging material would I use? The front port is located in the front bottom and is a rectangular opening. The system is not played at extremely high volume.
Thanks for any suggestions.
 

Thanks wtf,
My system isn't quite the same as yours. I have two 10" Klipsch subs but one is sealed and one is front ported. That's why I considered plugging the ported one to bring the two closer in performance. Yes, I am using the ICBM in stereo subs mode. ICBM manual suggests setting the crossover on the subs to their highest setting and then select the actual crossover point on the ICBM. I assume this is the correct way to incorporate the unit with the subs? Thanks again for your suggestions.