For several years I've been using Corelli 370s, but I wish to change for a more robust sound. I tried some weeks ago a set of Helicore Hybrids and like it very much. So I searched this forum for advice, and someone somewhere said that Hybrids have a short life; he recommended Pirastro Permanent for long life and robust sound. I'm looking for thick sound on E and A (though my 370s' A is fine). Any advice on that?