I own a pair of Von Schweikert VR-1's that I have on stands but have read that they perform well on a bookshelf as well. You can get some additional information from their website at the Von Schweikert site.
I've also owned the Polks you mentioned and I would forwarn you that I would imagine that the bass response from those would be overwhelming if put on a bookshelf. The VR-1's are much better and even-tempered speakers than the Polks in my opinion.
The one thing to keep in mind about the Von Schweikert's is that they take 100+ hours to break in and the change is dramatic. If you pick some up be prepared for the agony of the first 100 or so hours - but, man, do they sweeten up from there on out!
I've also owned the Polks you mentioned and I would forwarn you that I would imagine that the bass response from those would be overwhelming if put on a bookshelf. The VR-1's are much better and even-tempered speakers than the Polks in my opinion.
The one thing to keep in mind about the Von Schweikert's is that they take 100+ hours to break in and the change is dramatic. If you pick some up be prepared for the agony of the first 100 or so hours - but, man, do they sweeten up from there on out!