For my loud and bright sounding cello, I combine Thomas Versum SOLO strings for the lower strings with the Thomastik Versum D STRING, which in my cello's case, sounds smoother and cleaner than the higher tension Versum D solo. I've tried the D solo but the sound becomes overly saturated and harsh. All Versum strings are favourites of mine, being both reliably responsive to play and long-lasting but I think the choice between the solo or original Versum string depends on your cello and it's OK to mix them up. I also sometimes use the Versum C string instead of the C solo. If you want a great-sounding, D string with staying-power and which doesn't need much playing in, I'd recommend the Versum D.