The Axiom subs come with a variety of ways to connect, and I think recently introduced a 1/4" option as well, not sure why. My Denon receiver has Sub Out jack which is RCA type connector that I run to line in RCA on one 350, then I daisy chain from line out RCA to Line In RCA on my 2nd sub.

M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85