I have an Onkyo TX NR1010 with the best Audyssey available and the sub eq ht.
Does this handle all the sub eq'ing that is necessary or something like a mini dsp still recommended?
I know the sub eq ht is for dual subs, which I have. Just curious if all that on board software takes care of everything.
It depends. Do you have a sealed sub(s)? If so, then EQ'ing the bottom end with some boost can make a fairly large difference. If you are referring to the high pass filter in a ported sub, then I would recommend using a MiniDsp or other similar EQ devise for that as the XT32 will not be able to set the HPF to protect your driver.
If the sub is self sufficient in its design, Audyssey does a really good job of EQing the response flattish and setting delays etc.
Do you have measurement capability? I assume you do since your talking DIY speakers and outboard manual EQ...... If not, your first purchase should be a USB mic and download REW or other measurement software. The Minidsp wont help you much without the ability to measure.
I have the older MultEQ XT and have found benefit in external manual EQ. Your version(Audyssey) has more filter resolution so IDK how much you will find it useful.