more power is always nice, but if theres a REAL 18w available, another amp might not be necessary to get some adequate thumpage. efficiency specs on these are pretty good with 97db-1w-1m http://www.amazon.com/MCM-Audio-Select-55-2952-Surround/dp/B008BWA09U/ref=sr_1_34
MCM's 8's and 10's with treated paper cone and cloth surround also having similarly-signifigantly higher efficiency specs than most for their sizes, and definitely so for their price ranges. their poly cone rubber surround, no.