Low cost subwoofer upgrade

Had you used one of the Rythmik's to preform the subwoofer crawl to locate your rooms standing wave bass modes to properly position them in, you might of arrived. Your conclusion using the Rythmik's would suggest your front wall location is a room null.  

You'll also be losing the Rythmik's substantially lower frequency extension and other sub-sonic benefits that your current -6dB sub-bass system speakers simply can't provide, regardless of the type of cable or termination.  

Speaker cables make a difference, interconnects make a difference, etc, i fully agree.

But... how fascinating this is!! your  sub's playing 20 to 60hz (mas o menos)? depending on where your crossover's at....and yet you changed a subwoofer's power cord and perceived a great improvement in "detail", huh??

Try again.....Turn your speakers off/unhook them and just have subs playing for a bit...wooomboomwoomboom it goes and that's all you're gonna hear for a bit. Now, swap the sub's power cords back and forth and let us know if you reeeeeallly perceived an improvement in "detail" or not!! i.e., an improvement in the 20 hz to 60hz woomboomboomboom detail!!!

Besides that, you have some nice speakers, the Voxativs, designed by a very smart engineer. Ms. Adler is very cool.

A speedy sub is the KEF KC62. I use it with the fast Magnepan LSR+ speaker.

You misspelled miniDSP. 

Hsu subs are pretty good for money. If buying used, try to get the more recent models.

B

I experienced it with the REL upgrade cables, though the standard ones are good and I use them in secondary system...