I can tell I am lacking the very bottom of the audible range
I read somewhere that these speakers are specified flat down to 23 Hz +/- 2db... This is simpy an amazing specification. There is no possible way you should be lacking low end if these specifications are correct...unless you have a very large room or something is wrong with the speakers.
What is your source - are you quite sure you are sending the full LF range to your speakers? Do you have perhaps a huge room size?