max input voltage advice

I have a msgeq7 circuit that I've used many times and works great from line voltage, however I want to install it in the casing of a subwoofer It'd be easiest to tap off the speaker wires for a source but I imagine that can be higher voltages of like 100v or so, unfortunetly the feed to the sub is a subwoofer out and isn't line voltage either would it be fine to use either of these? The msgeq7 has an input impedance of 1Mohm and goes thru a .1 uf cap and 33k resistor

what do you feed into the sub, is it line in with an internal amp, or is it a speaker in a box

Firstly speaker voltage is likely to be too high (although a voltage divider could be employed).

Secondly the feed to the subwoofer is already low-pass-filtered, well its very likely.

Thirdly if you want to graphic equalise the signal to the speaker you have to do this before the amplifier, so its too late in the chain to sample after the amplifier, surely?

Sorry I should have explained the usage, its being used to trigger leds but only in the <300hz range desired
The sub is fed line voltage I realized since they wouldn’t have rca for speaker level( shitty manual made it sound like it was speaker level)
however id like to not tap into the rca cable
and I took the plunge and did connect it and it worked perfectly… for 10 seconds
It took the speaker voltage no problem, however I had not realized that I couldn’t connect the input the same way I did when I was testing the device with my phone
For my phone I had to connect the ground to the ground of the phone(speaker -) and then connect a channel, I forgot that in the application with my sub that the speaker - isn’t ground : (
needless to say I blew my 500w amplifier
so now for the next few months as I save for a new amp I have it connected to the speaker as a microphone and works pretty well when I play music(some nuisance flashes while driving tho)
when I do get my new amp Ill make sure to only connect the channel input as it already shares the ground with the amp and that’s what fried the amp, the alternate path to ground thru my board : (
expensive but lesson learned