I have a 2x12 cab loaded with two Eminence legend GB128 - each speaker rated at 8 ohms and a 15/30 watt orange clone head.
My problem is that both cab speaker wired parallel ( a total of 4 ohms impedance ) into the 4 ohms amp output, have significantly LESS volume that one single 8 ohm speaker. I also wired them series, so 16 ohms, and windows shattered. I'm not really good with electronics but shouldn't the power/volume be the same if the cab and amp have matching impedance. Am i missing something ?

Any help is appreciated, thx
yes, i wired them correctly. The clone was built by a guitar tech, i wanted to check some advices 1st before i call him. Its still a bit blurry for me this whole impedance thing, i read that different impedances in a guitar amp will give a different load down to the cabinet and the way it works the speakers, however it said nothing volume-wise, which i feel should be the same regardless of the load, if the impedance is matching