A preamp is before the amp so maybe you are talking about a more powerful amp. For me I rarely need the preamp since I moved away from turntables.
When matching speakers it's all about Ohms. Then Watts. It's fine to drive a speaker with less Watts. Usually you never have a true drive issue but let's hear why you think a preamplifier was called for.
I have a type r Swr-1242d and I'm not sure if my carver pm-1.5 power amp will need a pre amp to run the sub or if the amp itself is sufficient. My receiver is an old jvc A-X900 which is running my 2 Polk audio towers. Please help