300B vs. KT88 SET?

Hi guys, I've heard so much ABOUT tubes that I want to try them. My speakers are very efficient, so there should be no problems with 7 watt SET amps. Unfortunateely, I can't find place to audition them so I need your help. There are number of amps available here on the Agon. Some of them based on 300B tubes and some are using KT88. Thouse that use KT88 are less expencive to buy, and so are the tubes.
But how different do they sound?
All you inputs and opinions are appreciated.