I bought a set of D'Addario Helicore Cello Strings for a recently purchased second cello (which was used).  The cello, from a reputable company, came with terrible sounding strings which needed immediate replacements.  Since I wanted to compare my two cellos by equalizing the strings and using the same bow, it made sense to order Helicore strings (FYI my primary cello came with the Helicore).  As stated in other reviews for this product, the strings made a huge improvement in tone and projection on my second cello.  The "o.k." cello became a decent one simply by changing the strings.  I was amazed to find that the Helicore strings made that much difference.  Now, I'm really sold on the Helicore strings.  I believe it's worth spending $100 on this set.  I highly recommend it.