After years of experimenting, and I mean REALLY trying everything, I am fully committed to Pirastro and their gut strings. Oliv cello strings, and in my case, the stark/thickest gauge, do absolute wonders for my cello. I pair the thick C, G, and D with the Perpetual Solo Strong A or Passione Strong A. If you find yourself in the market for new strings and have a luthier close by for any transition adjustments needed (grooves of nut or bridge), give them a try. Give them a REAL TRY, like at least a couple of weeks. You may hate them, or, like me, they may change your life forever, spoiling you with a new type of sound that just isn't possible with an all steel string setup.