Best subwoffer crossover with room correction

Room correction DSP or using the internal EQ won't do as much as placement will for bass (and all speakers). If you're well versed using REW you will need to place your subs in various spots then measure to find the best spot(s). Once you place them in the best spots you can, then using DSP (think a MiniDSP for example) will help a little more by making frequency adjustments and also phase adjustments. Adjusting the volume levels will be up to your taste. 

Lets start with placement.  Use the AM Acoustics room mode simulator to try to find the best location for the speakers and sub.  Try to keep your speakers and listening location out of the worst / lowest room modes.

Next, you should take Vandersteen's advice and use a high pass filter.  Vandersteen sells them directly. Try to use a subwoofer for 10 Hz wide space is madness.  Also keep in mind that the specs are garbage when the speaker is in the room, but many an audiophile who has attempted minimalist subwoofer use has become a convert to using a high pass filter, and one of the main reasons is that it makes integration a lot better and easier.

Thank you for your time and detailed technical explanations. I appreciate your insights. While I was initially hesitant to add a subwoofer to address the 3–6 dB dip at 10–20 Hz, I understand the importance of placement optimization for the Vandersteen 2CE speakers. I will continue experimenting with different placements to achieve the best possible sound quality.

Mahalo and Aloha,

mschwabmmd

OP:

By letting the sub take over more Hz you not only reduce the distortion, and increase the dynamic range of your mains but you also make it possible to introduce DSP that is ONLY in your bass. That is, any problems you have in the 20-80Hz range move over to the sub and become easier to manage. 

Done well a subwoofer should make your speakers sound glorious instead of incrementally better.