REL pioneered the speaker level connection for better integration, but these days many other manufacturers have followed them.
From what I could find, the Energy S10.3 is not a particularly bad subwoofer at all. In my experience the sound quality of a subwoofer depends more on room integration than on the sub itself. I started with a very good sub (a B&W PV1d) and even that did not sound great until I added an Antimode 8033 for room equalization. The result was suddenly far tighter 'faster' and more 'tunefull' bass. My next upgrade will be a second PV1d to achieve smooth bass over a much wider listening area.. See here for multiple subs: http://www.acousticfrontiers.com/20101029using-multiple-subwoofers-to-improve-bass-the-welti-devanti...
From what I could find, the Energy S10.3 is not a particularly bad subwoofer at all. In my experience the sound quality of a subwoofer depends more on room integration than on the sub itself. I started with a very good sub (a B&W PV1d) and even that did not sound great until I added an Antimode 8033 for room equalization. The result was suddenly far tighter 'faster' and more 'tunefull' bass. My next upgrade will be a second PV1d to achieve smooth bass over a much wider listening area.. See here for multiple subs: http://www.acousticfrontiers.com/20101029using-multiple-subwoofers-to-improve-bass-the-welti-devanti...