moskaudioThis indicates for them to sound their best in the bass, an amp that has good current delivery <100hz.
Impedance reaches a minimum of 3.75 ohms at 66 Hz and a phase angle of –47.96 degrees at 83 Hz.
Read more at https://www.soundandvision.com/content/polk-lsim707-surround-speaker-system-ht-labs-measures#fIW7rJB...
A good solid state amp that can keep increasing it’s wattage for every halving of impedance, is an indication that it can deliver current.
EG: A theoretically prefect amp that delivers current, none can do these prefect figures in real life, but some get close.
8ohm 50w
4ohm 100w
2ohm 200w
Cheers George