Need an amp with a 'turbo' top end

Are you sure it's an amp issue? Ohm Fs are an older design and can be subject to many issues these days.

The published specs for F's on the Ohm website indicate that the top end extended "only" to 17000Khz, which is lower than most modern speakers.

What is the rest of your system currently?

I remember selling those at Tech Hi-Fi back in the 70s. Pretty powerfull bottom but, seemed to always lack the top end. Maybe a Bryston or Krell might help...

I doubt that a brighter amp would help, but then again, this is a pure guess, particularly because you never mentioned the amp you are currently using.

I would consider adding a supertweeter, something like the Elac, which has an omnidirectional dispersion pattern that would fit with the Ohm speaker.

The other alternative would be to get either an equalizer or a linestage with some form of tone control.

Try one of the class D amps, they did wonders for my old and lazy Mirage M3s, really brought them to life.