The recommended hock up for Sapphire II and Sub 1 were to run one pair of cables to the sub in, than a second pair from the sub out to the mid-driver on the sapphire II and a third cable to the tweeter on the Sapphire II.
I ran my Sapphires and Sub 1 like that for several years, but felt that the bass was too shy.
I ended up removing the - I guess it's called the low pass filter - and moved it into the Sapphire one in front of the mid-driver x-over input.
I now use an external x-over from Paradigm to run the Sub 1s - powered by an old Adcom 555 power amp.
SO I have my pre-out run to the Paradigm x-over, crossed the Sub over around 60 Hz, than the signal continues to go to a Marchant Bassis, Bass management control, and from there to a slightly tweaked Adcom 555 to the Subs.
Than I have one pair of cables run from my tube amp to the Sapphire III (upgraded mine from the II to III). Internally I put both, tweeter and mid-bass inputs on one post, to eliminate a sound degrading bridge on the 2 sets of posts.
This may sound a little confusing, but works wonderful for me.
Being able to give the sub their own amp will increse the performance of the sapphire at least by one or two levels. At least in my case, since my tube amp only has 45 Watts. Using a high powered SS amp MAY have enough power and control and give you a different result.