Suddenly i got a hint of connecting my powered desktop T40 speakers to my soundblaster z card headphone out with amp. Sound/audio play improve a big amount compare to the usual 2v line level output. What come to my mind is that 2v is very small voltage which can only drive 1m length of line level cable. Longer than that, quality and performance will drop. While trying out different length/size of 3.5mm line level cables at the headphone out with amp, i found out that even a reduce in size and length from a thick and 2m length cable make improvement to sound/audio. A search on the internet also can find headphone amps that enable connection to both headphone and powered speakers. Anyone has opinions on this and using headphone amp for powered speakers can kindly share it here.