How big is your room? How far are you from your speakers?
I use an older Parasound HCA-1000A, which has very similar specs to the A23, with a slightly less robust power supply (which is why, I assume, the A23 is rated at 225 watts into 4 ohms while the HCA-1000A is rated 200 watts into 4 ohms, although the 8 ohm power is rated the same).
I'm driving a pair of Onix Reference 3 floorstanders, which are 4 ohm, 90 db speakers. In my 9x13 room, with a 7 foot listening distance, I can get easily get into continuous, 95+ dB listening levels when playing music like live Deep Purple. However, if I ever had the desire to play louder (and I do not) then I'd probably want more power.