Hi Renato,
Both the E-560 and E-600 will drive your Sashas.
The quoted Accuphase power ratings are very conservative.
Though they're both rated at 30 watts into 8 ohms, they don't start to clip until almost double that power rating, and they both double their power into 4ohms. ie you'll have approx. 110wpc into 4ohms.
Look in your owner's manual for the graphs, or read Audio magazine (German) for their test ratings.
The Sashas and Summit X have impedance dips that can make them difficult to drive properly - Sashas at the bass, Summits at the treble.
Update: set up the Summit X's last week with my daughter's help, but the final settings, while excellent on my test track, meant bloated bass on a Jennifer Warnes track, and no drum 'thwack' on Take Five. Aargh.
Haven't previously experienced this when setting them up.
This hobby! :skeptical:
Back to the drawing board.