Easy and work project

I saw a question in my Youtube video about how to combine speakers for one amplifier unit without making any damage to an amplifier.  An speaker impedance must be match or higher than an amplifier manufacturer specification, if you use lower speaker impedance than an amplifier specification, your amplifier may end up damaged or make a fire when you play loud music. A commercial amplifier can handle between 4 - 16 ohms speaker impedance and maybe lower to 2 ohms for car subwoofer amplifier. but in a question, he asked me how to combine 3 speakers @ 6 ohms load to one amplifier. The simple solution is to make 3 separate amplifiers and share same input, but it makes the circuit more complicated and uses many electronic components. However, if connect all 3 speakers in series, it will make impedance equal to 18 ohms and it makes an amplifier output drop so much. So, I use 2 speakers connect in parallel and series to other speakers like an image below SP 1 and SP 2 impedanc