As an admittedly broad generalization, my experience is that a "lively, energized" sound is most reliably achieved in your price range using very efficient (93dB+ sens, MINIMUM impedance dip 6-7 ohms)loudspeakers with tube amplification of modest power (30-50W/ch). Omega Grande 6s powered by a 30W/ch 6L6GC-based amp cranks out beautiful, energetic music in my basement system at volumes that'll piss off even the most understanding spouse.
What I've learned is that amplification and loudspeakers cannot each be considered in isolation - it's as if they are a single component.
If you're not wedded to very deep bass (the aspect of reproduction I'd personally compromise on in your stated price range), loudspeakers in the range of -3dB at 50Hz, augmented by proper in-room placement, will give you a very satisfying low end leaving out very little musical content for most genres. Also, there are a number of nice integrated tube amp choices for $500-$1000 used, such as the Consonance Ella (I've owned one). If you've no experience with tube amps, know that bisaing is really easy for most and that their "extra maintenance" versus solid state is, IMHO, generally overstated.
Just a bit more grist for the mill, FWIW...
Good luck,
jb
