connecting subwoofer via speaker terminals

@gdaddy1 understood, thanks!

@fastfreight  +1

My speakers have good bass to about 45hz so let them do their job. The subs low pass is set at 60hz.  I tried using high pass filters but, like you, I much prefer the full signal going to the mains. I also agree the imaging to be better/cleaner as well. Keep it simple!

So much better ultra deep bass when using the low level inputs to the subs rather then the high level.

@lloydc hasn’t said if his sub is equipped with speaker level inputs, and if it is I endorse using them, as @gdaddy1 and @fastfreight have suggested. The cases where this is not advisable are with monoblock amps (unless using a sub for each) or with some Class D amps that don’t have a common ground, like NAD. 

OP has also not said if his amp has a processor loop or pre-outs and amp inputs, so incorporating an active crossover like @elliottbnewcomjr suggests may not be an option. Plus, in my past experience these can place an unwanted veil on the upper range, as few of these gadgets meet high end preamp standards. 

Thanks for all the responses! I do monitor them.  I will look for subs with speaker-level inputs.