Increase total Speaker Impedance -- Potential Solution

Hi All, 

Years ago I asked about using a resistor to increase the total impedance of a speaker -- I know that's a bad idea now because Impedance is NOT the same as resistance. I did get a pair of Paul Speltz's Zeroformers and they are great!

However, reading more about this, I thought another, more cost effective solution. Why not just buy a low cost, 4 ohm speaker, remove the diaphragm inside, and series-wire it? I'm reading some of the Zeroformer's technical documents and it sounds like it's rather similar to a speaker coil that doesn't produce any sound. Therefore, if I just series-wire a 4 ohm speaker to my existing 2 ohm speaker, wouldn't the total ohm seen by the amp be 6 ohm?