Can Dynaco ST-70 Drive Polk Monitor 10?

I'm pretty sure that you should be fine. I've used ST-70's to drive speakers anywhere from 85-93db efficient. I will say that most of the less efficient speakers I've used were simple 2-way loads, so it's possible that the 3-way/4-driver load of the Polks won't agree with the ST-70, but I think that's unlikely.

should be sweet.

I don't think there will be a problem driving the speakers, but....

While the Polk was a great value in its day (IIRC - and it's been a long while), it always struck me as just a bit soft in the bass. Similarly, the ST-70, while a really great amp in many ways, is not the last word in bottom end grip. So....while this might not be a match made in heaven, I'd still think it would be kinda cool.

Marty

You should be fine. I drove a pair of the Polk Monitor 7b with a NAD 3020 rated at 20 watts per channel (though it was very conservatively rated). When I bought that pairing I auditioned the 3020 on a set of the Monitor 10s and went with the 7s due to size and finances. The dynaco should work very nicely.

Yup 3020/10s - first system out of college - oh, yeah, and a Thorens.