Amp choices

Been running a 7300 bareback on an EFHW. I’m in an HOA so no permanent outdoor antennas. Mine’s in my attic. Routine QSO,s on 20 M and up from Russia to Chile to Hawaii. Thinking of an amp. Don’t want 240v or more than about 300 W. Amp is for a little more punch, but especially 40 and 80. Built and tuned antenna so 7300 internal tuner tunes from 10 M up, but can only talk 4-500 miles on 80, maybe 1000 on 40. Probably a take off angle issue but my options are limited. Recommendations would be well appreciated.