I spoke with Mr. Vandersteen about the 4's. The Full Range switch is there for testing purposes only, he says there is no internal crossover.
He also mentioned that some models of the WX-4 had dip switches to allow you to match the input impedance of the power amp. Otherwise the actual crossover point may not be the 80 Hz design value. My unit doesn't have these.
Unfortunately, the WX-4 doesn't seem to to be powering up. I need to check the fuses inside the WX-4, or maybe the power indicator LED is out.
I would like to try bi-amping these, I imagine they will sound fantastic.
He said that the woofers in these were made by Dynaco and replacements are not available, so be careful not to blow them!
Time to trouble-shoot the WX-4. To be continued ...