Really? I thought rainbow were better speakers. Just not as efficient. Hmm
In any case. If you are running ms-8 power then worry about efficiency. If you are amping. Dont worry about it unless you want to blow your ears out. The 600/6 will get plenty loud with rainbow or similar
FS:Sub Amp - works w/ Technic harness! MRD-M300 - cheap
DON'T BUY FROM RAF555!!!! Promised fix! - strung me along til Paypal dispute period expired!