How can a 30 watt, 28 year old amp sound more

I recently connected a 30 watt NAD 3130 integrated to my 85 db efficient 8 ohm ATC SCM 12's. The amp it replaced was a 120 Watt high current and very highly rated amp. The sound I got was bolder, deeper, punchier and more dynamic. It took hold of the mid/woofers and whipped them into total submission. What the hell?

What would account for that? I always thought more watts, high current equals more dynamics and control. This proves me wrong. The NAD is also a high current design, but 30 watts??? is it damping factor? is it slew rate? the 120 watt amp has a damping factor of over 500 and is stable to 2 ohms. The spec on the NAD does not include damping factor or slew rates. It too is stable into 2 ohms.

Can anyone explains why in this case, watts did not matter? any idea what makes this 30 Watt integrated sound so bold, dynamic, and punchy?

Thanks