As a temporary subwoofer, I would like to connect a Logitech Z5500 sub to a Harman Kardon AVR355 (354 in US). Is it possible?
Can I connect the LFE output from the amp to the coax input on the Logitech Z550 input box? This sub has an external input box with coax-optical-analog connected to the active sub with a special cable.
A/V from a BR player comes in through HDMI and front/central/back speakers are connected to the HK amp in the usual way.
I thank you in advance for your help.

Can I connect the LFE output from the amp to the coax input on the Logitech Z550 input box? This sub has an external input box with coax-optical-analog connected to the active sub with a special cable.
A/V from a BR player comes in through HDMI and front/central/back speakers are connected to the HK amp in the usual way.
I thank you in advance for your help.