Magnepan 1.7 owners and subwoofers

@schubert  I must agree with @dsper  in that there is nothing wrong with W4S amplification and bass control. With a damping factor of 2000 the bass is tight and powerful. Can't imagine it wouldn't do the job with Maggies.

I love my SVS SB-3000 for about $1k and it has remote control. It's sealed and tight. If just running one I'd also opt for center placement for the ability to use a higher low pass frequency if necessary.

IMO if you want to use a sub for music 2 channel, you should place the sub in a center channel position(between the mains). Its the only way to get it to blend IMO. Sounds fantastic between the mains and can even be set at a high cross over setting

IME, I would agree with this. Dead centre between the speakers produced the best result. A caveat, the sub needs to be reasonably high quality. If the sub is poor quality, you will get poor results wherever you plonk it. I learned through the hard way.

Most Magnepan-subwoofer setups suffer from what I call 'timbre mismatch', regardless of the crossover and level settings. And that is made worse by subwoofers that are home theater oriented, tuned for output not musicality. Certainly crossovers with a high-pass and lowpass are preferable, boosting power handling and panel output capabilities. However, my headbanger, tweeter melting days are far behind me, so lack of a high-pass function isn't a deal-breaker for me. 

Stick with the hifi version of the subwoofer offerings, and a smaller driver (8") and your timbre match issues will be minimized. REL and SVS, as well as KEF all have great offerings that meet those requirements.

Coincidentally, my experience with both  Magnepan and powered subwoofers goes back almost 50 years, both as an audio engineer and as an audiophile.