Preamp or power amp has more impact to resolution?

Well said Salectric - that is my conclusion as well on all points.

...which upgrade that can provide more impact...

... at the end of day: the Quality of your Speaker Drivers and the sensitivity after
the X-over

speaker upgrade...

you could also add, do consider the integrity of the designer and builder of your prospective speaker.

Wow, seems that I need to change the whole of my system :)
Seems that I have to use my charm to let dealers to show case, see and let my ear to decide.

Thanks again

Two things, source and preamp. I recently replaced a laser in an older Rega Apollo CD Player and that $25 part just made the CDP sound so much better in clarity/resolution. It has me thinking that over time, the laser gets worn out. Clarity and resoltion were a hugh improvement. I will be experimenting with older CDPs to see if this is consistant. That being said, the preamp also has a big impact on clarity/resolution. I build direct heated triode, transfomer coupled preamps and no conventional preamp can match what this does basically because there are no caps in the signal path.

Happy Listening.