Subwoofer for music, how low?

Very, very little music content is in the 20hz range so I wouldn’t let that be a major factor in sub selection. 27hz is plenty low, and REL is extremely well regarded..

Like everything in life, it comes down to trade offs & compromise. Yes, 20hz has been the mark we have been taught to shoot at. But in reality, very little music goes down to 20hz. Then too, there is the trade off of size. In order to get down lower, you need a bigger box. Plus it costs more. Then there are the specs. Is it rated conservatively or is it rated better by manipulation for sales.

The nice thing about the Rel is how easily it blends and how much bigger it makes your main speakers sound. Plus it uses high ;level input from the speaker terminals on the amp. I have had them for 20 yrs now and was one of my best upgrades.

Merry Christmas to you ! 

I have two REL T9i and love the sound.  They are subwoofers with sound that contradicts their specifications.  

Mine play down to 20Hz in room at the listening position and have more than enough power, punch and impact in my med-large room. 

Of the several other subwoofers I have tried the RELs are the only ones to not color and obscure the midrange and they blend perfectly well. They are so easy to adjust so that they blend with your system- think days instead of months.  

No other subs for me.  Peace.