Originally Posted by Audiojan
Power has become very much less expensive... 15 years ago, you could hardly find a class D amp... so yes, you will see more power today then you did then.
But that a side... do you REALLY need all that extra power? If you have a larger room and/or you usually crank the volume way up, then you might, but if not... well... you might be fine with you 15 year old Mirage... that is not a bad subwoofer at all.
As Audiojan says, now, digital switching amps are pretty cheap, and work well in applications that are limited to 200 Hz and below.
As has also been suggested, 15 years ago, response down to 25Hz at 105 db was considered very good performance. Now, people are looking for 105 db at 15 Hz and greater overall output as well. This takes more amp power.