What are the best subwoofers you have heard for music. Speed, Musicality and integration

Does anybody have a theory about what specifically makes REL subs integrate so well?  I've never heard one.  Bottom firing subs tend to have more even in-room response.  Subs with smaller woofers have less visceral transient responses that may mean they draw less attention to themselves.  If they know some secret nobody else does they're not going to advertise it because that would be stupid.  

Having two in my system that integrated very well and fairly easily, I would say using the Speakon high level connection helps tremendously.  They get fed the same signal the speakers do.

calvinj

REL is the best Sub in the business. 2nd is Sunfire (smaller in size yet still packs a punch (no pun)).

Happy Listening!

@jafant i had a sunfire true super jr that I loved.  It was such a great sub but it died on me.  It got replaced by two RELs.

@calvinj 

i started a REL thread in the speakers forum a few weeks ago.  In a few days I will have a T9x installed in a secondary system