The keyboards that used the LA sound source were the first E series Roland came out with back in 1989-1993 if I remember. They were the E10, E20 and E30. The sounds of these 3 keyboards came from the D10, D50 keyboards.

I owned a Roland E16,E28,E38,E66 but I always felt my friends old E30 sounded better. Only the E10,E20,E30 used LA....after that Roland used GS sound source if I'm not mistaken. The only E series that I felt sounded terrific was the Roland E86. The Roland E30 had only 128 sounds but they were stunning. Hard to find a used one.