If you by splice, you mean connecting in parallel, you are reducing the resistance.
1/R + 1/R1 + 1/R2 + …
If you are splicing two speakers that are 8 ohm, they become 4 ohm combined.
If you splice them in series:
R = R1 + R2 + …
It becomes 16 ohm.
I’m not an electrical engineer, but if the amp wasn’t designed to operate in that range, you may want to avoid splicing. [/quote]
That’s correct. It’s always OK to wire more speakers in series but then each speaker has to share the current and you will have to crank up the amplitude to compensate. Generally, it’s also OK to wire one more pair in parallel unless the amp is a real cheapo.
Keep in mind that it’s really AC impedance we’re talking about here, not DC resistance. Therefore it’s only at certain frequencies that the amp will see a tough load and be in danger. Most music isn’t going to be a problem, you’d only be in trouble if you connected a sine generator and dialed in the frequency where the impedance became too low for the amp (it’s like shorting the output terminals then… not good).
I would recommend a speaker splitter box. They’re cheap and they maintain a proper load to the amp. Or, wiring one speaker in parallel and that pair in series will bring you back to original impedance (~8 ohms usually).