I have a hughes & kettner BASSBASE 600 (1994, but the same as the one they make now)
The manufacturer's site says it's power output is:
Output Power (RMS):
410 watts/ 8 ohms, 650 watts/ 4 ohms, 840 watts/ 2 ohms
Output Power (DYNACLIP):
550 watts/ 8 ohms, 840 watts/ 4 ohms, 1010...