how much power needed for mid-high frequencies?

Hello out there.I`m using a JRDG Concentra 2(250w in 8 omhs)to drive my Apogee Duetta signature(4 omhs & inneficient speakers.)I want to drive it in a vertical amplification way using a tuve single end amp for the midrange/tweeters.

How much power needed for mid/highs?

Will be necesary with volume control?

In a $4000 TO $5500 range which?I like a 300b or the new Art Audio PX25(but is just 6 watts).

My sistem:
SCD-1 as a transport
Cello reference d/a(108db A weigted)
JRDG Concentra 2
Apogee Duetta signature

THANKS, for any help about & sorry for all these questions.