The Quatro Woods are not sonically the same. They are, in fact, built differently inside. The Quatro Wood has a different base enclosure and the 5A tweeter housing. They also have the 5A crossover. Richard Vandersteen says that they are more sonically clear from top to bottom than the Quatros. The differences were nessessary due to the fact that a rigid cabinet, if left uncorrected or compensated for, can cause "smearing". Therefore, these speakers resemble 5A Sig. in many more ways that the Quatros do alone.