Thanks, I've been reading a bit on phase shift or angle, same thing ?? Still trying to digest it, from one article it appears they're saying not to worry to much about it in an amp.
In one sense, you can consider the effects of phase angle being built into the frequency response (which represents voltage sensitivity over the full bandwidth): whether the phase angle is 0 degrees or 60 degrees, the voltage demanded from the amplifier remains the same. As a result you don’t have to worry that an amplifier is going to have to swing loads of extra voltage and current in order to cover the effects of a difficult phase angle.