String Combinations

[Sergio Netto]

I was using D'Addario Helicore Pizzcato medium strings in my bass and their sound was pretty good for jazz pizz, but when I bought my first set, the E string broke when I was tunning it. I contacted D'Addario and they sent me another E string. Then when I bought my second set of the same strings and put it on my bass, the same problem occurred with the E string. It has broken at the same place, near the roller.
I read in internet an advice for blending the Spirocore S42 E & A Med. double bass strings with Pirastro Obligato D & G bass strings.
I'm currently using Thomastik Spirocore Solo medium, but I don't like the D and G sound pretty much. I would like to try mixing the Spirocore E and A with Pirasto Obligatos D and G, but it's an expensive experience.
Can anyone help me?