Jose, have you given any thought to sound stage (the 3D aural canvas where instruments originate), imaging (accurate placement of instruments within the sound stage), time alignment of your speakers at your primary listening position, addressing room nodes (where reflected sound waves interact with the primary sound) for each speaker at your primary listening position, or indeed any aspect of the sound other than loud and from everywhere? I mean, you can sit in your car and get that.
If you've got great speakers that are properly time-aligned and you're sitting in the sweet spot, you can get the immersive sound and experience your audio nirvana with just two speakers.
I think you should take yourself and some of your favorite music, maybe a blu-ray or two, to a local brick and mortar audio shop -- not a chain like Best Buy, but a locally owned business selling PSB, Paradigm, GoldenEar, or some other higher end speakers. Plan to spend at least a couple of hours if you can. Let them demonstrate how a well-executed home audio system
can sound. I think by pursuing your current goal, you'll be doing yourself a disservice. You simply don't know what you're missing, and that's not an insult. I just get the impression that you haven't experienced what the rest of us have yet. You don't know what it is that you don't know.
The situation is: if you connect two 8ohm speakers, you have a 4 ohm load. Essentially the amp label is saying the amp will be damaged if the impedance goes lower than this.
In series, two 8 ohm speakers would result in a 16-ohm load. Two pairs of 8 ohm speakers wired in series-parallel will present an 8 ohm load (8*2 in series = 16, two 16Ω pairs in parallel = 8Ω). But each will have 1/4 of the power. Wayne has it right in post #4.
