best inexpensive tube integrated

I just bought a pair of klipsch heresy speakers in mint condition for a bargin. Ive always wanted to experiment with tube amplification and I think now is the time. I know very little about them(tubes) and want to try them out at a minimum of expense. I paid 350 for the speakers and therefore would like to keep my budget below 700 for a tube integrated. I am not against used equipment. Is it worth a try or is my budget too low to jump into tubes? suggestions please!