Subwoofer or New Speaker


Subwoofer or New Speaker?
Today I have a pair of Wilson Audio Cube that I use with Audio research VSi60.
Am generally satisfied with the speaker except that I feel it a little thin in the bass.
The question is. Should I buy a newer, modern speaker or a Subwoofer?
(Tried with a REL T1 it felt way too slow.)

titus1