How many watts per channel should I be using when

I've been using a Tandberg 3012 int. amp (100 wpc) with my Polk RTA 12's for the past 25 years. Lately, I have been blowing tweeters when playing the system at high volumes. I suspect that my amp isn't up to the same specs as when it was new. It makes me wonder whether I should now be considering buying a more powerful amp that would play at higher volume with less distortion and hopefully, not be blowing my tweeters. I was wondering if anyone is still using these speakers and what kind of amp you're using.