Amp to Add Dynamics & Detail to 'Polite' Speakers

I'm looking for an amp that excels in dynamics and detail - I'd like to impart some 'life' or 'zip' into speakers best characterized as a bit 'polite' sounding. Looking for nicely extended highs with slightly lean and tight upper-bass.

I'm taking a little hiatus from tubes, so solid state or class d amps only. I figure around 250 WPC into 4 ohms and around $3k new or used.

What else can be done to push a system in this direction - silver cables?

Thanks for any suggestions.