@JOHN FICKEL There could be some cancellations of certain frequencies. The best way I know to find out for certain would be to grab a calibrated measurement mic and measure using Room EQ Wizard. Position, measure, reposition, remeasure, change the phase of one sub, remeasure, and go with the configuration that gives you the fewest dips. The peaks can most likely easily be flattened by YPAO.
You could order a UMIK-1, perform the measurements, then resell the UMIK-1 on eBay and easily make back most (if not all) of your money. Others would be willing to buy it from you at near full price just to avoid having to wait for shipping from China. Or just hang on to it. A measurement mic is nice to have from time to time to answer questions such as this.