I went through String madness when I got both of my Kentucky's. After many,many sets of strings I found that each of them liked different sets? My KM1000 was a huge fan (or should I say I was a huge fan) of the D J-73, I tried the old bluegrass standard D J-74's but it was just a bit thick for my taste, so the 73's is all I put on it any more. Now the KM505 liked the lighter set of strings, just sounded better. I just put a set of D J63 (?) nickel on a MK that my sis in law is playing, she is new and has the tender fingers and she REALLY likes them as they are not as tough for her. However, I must say I probably went through 12-15 different sets before I got one for each Mando that I was happy with. Interesting though on that MK I changed the tail piece to solid and put those thinner strings on it, WOW, it made it twice as loud!! Try and Try till you get somehthin you like they are out there, but for me I had to change a ton before I found what I was happ with.