Vandersteen 2CE amplification jumpstart-cables,sub

I have the Vandy 2CE s and they seem to need a little more kick to drive them. Right now I've got a pair of Quicksilver Silver 60s w/ EL34 tubes but the bass and "drive" seems a little lacking ?(esp. w/ phono). I've been thinking about the following approaches, but don't know which will give me the best bang for my buck:
--I could switch out the EL34 tubes for KT88s.
--I could upgrade my Audioquest Midnight 2 speaker cables.
--I could add a Vandy 2W sub.
--Are the quicksilvers a good match for the speakers?
I'm using an AR SP16 preamp.
All suggestions are greatly appreciated.
The amps, while very good, are not enough for the Vandys. They really need 100 watts to deliver their best.
I assume buy your choice of speaker and amplifier you appreciate musicality. Your speakers will preform better with more power but kt-88 will not give you the same beauty in the midrange. the sub is not the answer. A better solution might be a mesa baron or music reference rm-9 or similar powerfull el-34 amp. Also a sweet sounding (like a meitner mtr-101)solid state amp with a pure tube designed pre-amp(like the Audible Illusions).
I disagree with both of my good friends. If you go to a 2w sub, you will cut the power demands on the main amps substantially cuz the lows will be rolled off at about 80hz. So you will get deeper bass, and teh amps will have to work less hard, and that will open up the mids and upper bass quite a bit.
I agree with Swampwalker dramatic performance improvement with the Vandersteen sub/ or pair Most cost effective as well.