Vandersteen 2WQ Subs and ARC Power amp

The crossovers are X-2B, fixed values no batteries.

Scott...don't you have batteries in the silver box where you change the input values?

This is a long story, so bear with me.  The subs came with WX-2 variable crossovers, with batteries and switches as you suggest.  But, they were single-ended with RCA plugs.  That is a non-starter with my REF 150, which is balanced input only.  So, I got "clever" and tried to skip a step.  I located a dealer who assured me that his pair of 150K fixed value crossovers (marked "X-2 BAL", no switches or batteries) would work well.  I purchased those, and here I am.

So to summarize, I have very faint bass from both subs when I have the main speakers disconnected, with high-bass content recordings and moderate volume settings on the preamp -- nowhere near the volume of the mids and highs from the mains. The forum contributors say the Vandy's are "subtle" but I have to believe thay should be louder. It is very, very faint. Strangely, when I tried without the crossovers, I got the same result.

I tried connecting them using the method suggested by REL for ARC tube amps, red to 8 ohm tap, black to 4 ohm tap (on an ARC tube amp, the 4 ohm tap is ground, I verified this with an ohmmeter). But that didn't improve things. I also tried connected the subs black leads to physical ground, same result.

I tried switching the phase, I tried different speaker cables, nada.

Are these things 100 lb weaklings? I just get very little sound out of them. When I place my ear next to them withe the mains on, I cannot hear or feel bass. I can't even tell they are powered on.  

Some folks have suggested calling Vandersteen, OK, but he's a busy guy and I figure he will just suggest going through the process specified in the manual, using the variable WX-2B's (which, at the moment, I don't have). The first dealer I called yesterday wanted to sell me the top of the line crossovers (X-5??) which are about $ 1400 and can be adjusted. The second dealer I called (the one that sold me the fixed value crossover X-2 BAL) thinks I have the right one now.

The amp has a 300 Kohm input impedance, balanced, and the second dealer assures me the 150K values he sold me are the right ones. He says I could go down to 100K but wouldn't expect a dramatic difference.  
I think my next step will be to do an internet search for some WX-2B variable crossovers and go at this problem that way. If any one has a pair of these they want to loan or sell, let me know.

@scottwsmith , 
Good info.
When I separate the subs from the speakers, yes, I hear a very faint sound from the subs. So, I suspect they are working. Moving to a lower impedance should provide an increase in bass response- at least it does for me.
What sound you do hear is the from the frequencies of about 100 to 80 hertz- there isn't a lot of music being made there- even with bass heavy music. Though it does 'flesh out' the upper frequencies.
This one of the beauties of the Vandersteen sub and its' implementation.

Now, I recommended calling Mr. V.
Mind you, I bought my 2wq subs second hand. When I called and left a message, Mr. V. called back the next day to discuss the issue.
I, too, had a problem with almost non-existant bass with my subs. 
It turned out I was using the wrong impedance measurement.
What I was impressed with was that Mr. V. called back the next day to see if I had corrected the problem.
Now, that is service above and beyond!
I also suggested PM'ing John Rutan(audioconnection). He knows just about all the brands and can give you great information, as well.
And, don't think he is going to try to sell you something. He is way too classy for that nonsense.
Though I might be wrong, I think your amp might have a diiferent impedance than listed. 
Perhaps contact ARC to make sure. Also, ask them what they think would be proper connection for a Vandy sub.
HTH 
Bob

Bob, I agree, not to run the subs without the crossovers. I was just explaining to the OP what the sound might be like without the crossovers hooked up. I have mine connected to my integrated amp"s processor's ins and outs. I one time forgot to engage the processor loop and the bass was boomy and bloated. In other words, that's the way it sounds without the crossovers. I did this quite by accident and would no way tell anyone to run the subs continuously without the crossovers.
Cheers,
Tim