i dont know where to put this except here
i generally am not a huge fan off 2.1 systems but realise that this is likely going to be popular but its clear that its not managed correctly by companies, nor is it well documented, nor is it well understood by the consumer
now let me refer to you a device that does this quite well IMO... not the best but better than most
the Arylic B50/BP50 is a well known pile of shit as seen here
www.audiosciencereview.com
when it was reviewed it had an excreble system where you could set the sub in 50hz increments
so 50-100-150-200 up to 300 i think
everyone hated this - but it did work as documented
so if you set it to 100 it sent <100hz to your sub and and > 100hz to your mains
people complained to arylic and to their credit they went overboard and now it does something like 50 - 300hz... in 1hz increments... which is way too much granularity... but they delivered I guess
it seems that manufactuers are just slapping in a sub 50hz filter on their amps and they reckon that's good enough?? is it though? I dont think it is
and that's before you get onto box placement and room acoutics but thats a problem for the likes of minidsp
i generally am not a huge fan off 2.1 systems but realise that this is likely going to be popular but its clear that its not managed correctly by companies, nor is it well documented, nor is it well understood by the consumer
now let me refer to you a device that does this quite well IMO... not the best but better than most
the Arylic B50/BP50 is a well known pile of shit as seen here

Arylic BP50 Preamp with HDMI ARC Review
This is a review and detailed measurements of Arylic BP50 preamp with internal DAC, phono stage, HDMI ARC and Bluetooth. It was kindly drop shipped to me by a member and costs US $99. Front panel doesn't hint at the immense amount of functionality BP50 provides. You get that from the back...

when it was reviewed it had an excreble system where you could set the sub in 50hz increments
so 50-100-150-200 up to 300 i think
everyone hated this - but it did work as documented
so if you set it to 100 it sent <100hz to your sub and and > 100hz to your mains
people complained to arylic and to their credit they went overboard and now it does something like 50 - 300hz... in 1hz increments... which is way too much granularity... but they delivered I guess
it seems that manufactuers are just slapping in a sub 50hz filter on their amps and they reckon that's good enough?? is it though? I dont think it is
and that's before you get onto box placement and room acoutics but thats a problem for the likes of minidsp