One of the things that attracted me to my RELs other than the deal I got buying them, is the "high level" input system from the amp, which allows a reproduction of the amp's tone and doesn't require long runs of single ended cable...simple speaker wire does the job. This series of RELs also has adjustability to fine tune the phase, crossover points and level that newer versions may not have in as much detail. Also, although I haven't tried newer versions of RELs, I can say the "Q" series I own sound spectacular within their limits...and those limits (low frequency range and level) are well within what's needed to charge the room with controllable bass for music...I have swapped in my 92 lb studio sub that's flat to 19hz, and found that extra low range didn't improve anything relative to what the RELs are doing with the music I like...plenty of drive and heft with the RELs.