All right, spend the weekend with adding the subwoofer and learned a lot. And failed a lot... also recognised that I am not good in buying gear in regards of getting the functionality I was thinking of ...
First, measuring position with the mark audios is the key. +/-5cm closer and the highs (+10khz) are there or not!
Second, the audient id14 mk2 has only stereo mirrored to six outputs. Even the headphone output can not be used with another signal.
So no chance for a high pass filter for the stereo amp via macbook + audient.
Maybe I will change the audient for another interface. Maybe, because even with not having the supposed functionality the quality of the inputs is really amazing for me.
Third, getting the svs pro version gave handy features and protected me from crawling under the table 100 times.. not knowing that the pro version has no high pass filter as the classic had, when using cinch line through, just gave me another moment of "why me".
So the maop first played in 2.1 with the svs sb 1000 pro via the audient using the 1+2 for the stereo amp and the mirrored 3+4 outputs form the audient for the sub.
As I switched to connect the stereo amp also to the sub the sound became better. Measured phase, etc. but simply plugging the amp to the sub improved the sound in regards of clarity. If not plugged to the sub, polarity changed a lot too.
My delay measurement s where not useful with rew... Was not able to get reasonable numbers for the sub.
Using the cinch input / output of the svs, and some eqs is giving a good result. Still the bass is not as sharp as it was with the yamaha hs8 or the hard core eq pushed maops.
In search for more clarity in the bass sound, I am looking for solutions. It is not as tight and sharp sounding as I hoped for.
I tried, plugging the bass ports. This helped to get some effect similar to a high pass, as the speakers do not perform well on the listening position without a lot of +EQ in the lower than 100hz area. And the whole bass peak between 40 - 60 hz from the speakers got removed that way.
So I wonder if, a true high pass via another interface would give a big improvement?
On the other hand, I would lose the improving of delay, etc. that appears by using the cinch out of the svs to the stereo amp.
Next weekend I will try, if I cut off the signals below 20hz (right now it goes down to 16hz adjusted to house curve with eq) and above 20.000hz, if this could improve the clarity of stage and sound.
Also setting the sub (right now on laminate floor) on a heavy stone plate could lower the vibrations in the floor and improve the sound of the sub, or?
To be honest I would struggle to provide the 'best' answer since there are so many variables here...
One thing is for sure: getting all your speakers on a separate channel (any of these shall work for that purpose) and measuring/setting correct delay values (along with proper lowpass and high-pass filters) will provide the best possible experience one can have with a subwoofer.
A correct high-pass would also take the burden off of your main speakers and that will definitely be audible (it even made a huge difference with my 15" Fane full range drivers...)