I had a total of around a half dozen SVS subs in succession with each one failing and being replaced under warrantee. One actually caught on fire internally and filled my room with acrid smoke which was choking. With each new sub, I tried a different offering paying the difference if needed so that I could see if there were better options to rounding out a muddy sound I kept hearing. Nothing I tried was satisfactory to me. I then brought home a monster Paradyme 15 inch power house sub which cost a small fortune and was lent to evaluate by a HiFi store. It was even worse! It was like SVS muddy sound on steroids and the dishes would fall out of the shelves in the kitchen due to excessive power.
I got my money back on the SVS subs, sent the Paradyme packing homebound and bought a couple of subs from Axiom who makes the Bryston speakers which I love. Voila! Perfectly balanced bass, musical, no nodes as they can easily be phased with the controls and best of all, no distortion at all with their DSP protection! I now have a total of 4 of their subs in my large room and the music is second to none. Keep in mind that I am all about music, not HT stuff; but if I do play a film, they are still fabulous. I actually opened up the subs to view the internals and they sport Bryston power amps inside :) massive linear power supplies with a huge toroid transformer. And very robust drivers all made in Canada.
I suppose this is all consistent as Axiom owns Bryston. The secret to great musical subs I found is to set the crossover frequency up high. I use the 150hz. setting and I cut off the lows at my main speakers (Bryston Model T Signature series) at around 80 hertz. I let the subs do the heavy lifting yet migrate up into upper bass/lower mids and have the big main speakers roll off below 80. It works very well. I find the most pleasing bass is in the upper ranges and this way the subs support it and the mains contribute.