I plan to upgrade but I'm stuck with what I have for now. I have a pair of M22ti speakers on the way. My receiver is a SONY STR-GX6ESII. It does not have a sub out jack or preamp outputs. My sub is a M&K V3B. What would be the proper way to hook up the Axioms & the sub?

The sub does not have a high pass filter.

I couldn't find a manual for a V3B but I looked at the manuals for a couple other M&K Subs. If you look at the back panel you may have 2 sets of binding posts, 1 labeled "From Amp" and 1 labeled "To Speakers." What you would do is run speaker wire from your Sony's main R/L speaker outputs to the R/L "From Amp" speaker binding posts, then from the R/L "To Speakers" binding posts to your R/L speakers. If there is a crossover on your receiver turn it off. Alternately I saw some of the M&K subs have RCA line-level returns. You would see 2 pairs of RCA jacks labeled line-level in and out. You would run a pair of RCA cables from your receivers "Pre-amp out" jacks to the "Line level in" jacks on your sub, then a pair from the "Line level out" jacks on your sub to the pre-amp inputs on your receiver. Again you would turn of any crossover in your receiver and use the crossover on the sub.