Help with Yorkville YSM1p studio monitors

[trashdinner]

I've got a pair of Yorkville YSM1p studio monitors and they both started to hiss after a couple of second/minutes. I tried ground lifts but nothing changes....

[musician2001]

I have the original m audio studiophile bx8 monitors and I recently lost the lf output amp in one of my monitors, I bought a new one and intalled it, then...