Tired of boring, polite, laid-back sound.....

In my experience, the speakers have more to do with laid-back vs. forward presentations than any component does. I have two pairs of speakers and three amps in my room that prove this point extremely effectively. I suggest you try some Triangle speakers. Arthur

Trying to hear "pulsating" from such a refined corner of the audio universe may not be possible when you compare to the brash upstarts here in the colonies (...er, United States).
At last year's Stereophile NYC spring audio show, Naim did provide energized, focused soundstage, along with sounds of real life, through their entry level electronics, and speakers, which might be in your stated budget. This year their website states their amps are "built to swing for another 25 years" so they seem compatible with your taste for action.
The NAIT 5i seems to be their current entry in the same range that impressed me at that show.

The "Brits" as you call them, are generally noted for their polite, laid back sound. If what you want is "lively, open, and energized", I suggest you consider something else (Adcom separates, Denon, Sony, or Onkyo receivers, Hafler separates, et. al.) See what some others might say. Good luck in your quest and happy listening.

I agree with Aball's and Listener57's choices. Naim and Triangle may be the most dynamic you can get at the $1K used level.

Besides Naim, Arcam could be your ticket. What is your planned budget again?