Subwoofer insight.

Without killing your budget I'm running a pair of small Sumiko S.0 subs with my Totem Tribe towers... It provides the perfect amount of punch needed for my dedicated 2 channel system.

The REL’s are powered geniuses ...they draw almost nothing from the amp via the Speakon connection.  Mains run full range.  No X crossover needed.  No extra interconnects.  No extra boxes with crap in them for the signal to be degraded.  Simple!

Do the math & call me back...

When we compared a beautifully crafted over $8k model with two DSP subs, its owner sold it the following week. The words this passionate Irishman used to describe it went well beyond junk.

Simply reading the manual it seemed obvious, they clearly aged out when the first set of preamplifier outputs became available.

I often consider sound reinforcement, recording, post production, and on and on, in other words the majority of the audio industry. Only one end of the high end uses that propitiatory high level subwoofer connectivity. 

That guy? He now has a full of crap DSP sub with thirteen remote controlled auto and manually adjustable parameters and filters within nine frequency bands from 15-125Hz. Six slightly augmented preset equalizations stored in memory for varying recordings or musical taste. Each setting shares a uniquely designed multi band crossover region that was also capable of closely matching his last two choices of main speakers systems sonic presentations rather than the half hearted idea of matching of a subwoofer to a speaker. Topping it off with really long RS-232 cables to two other crawl tested slave units complimenting his all tube vinyl based system. Big analog fan. 

Speakon connectors are just speaker connectors. No different. Almost all subs have them.