Advice for upgrade

Hi all, I have some questions and need some advice for my system. Current equipment: source: Apple Music on Apple TV > optical toslink to rca dac > Yamaha AS 501 > KEF Q150 Speakers + SVS sub Sb 1000

I want see which part should I upgrade first to get maximum results. I am deciding if I want to get the towers BMR or Monitor BMR. I get better sound quality when I use MacBook toslink instead of Apple TV. Are there any preamps with earc? Arc doesn’t support lossless like the Eversolo. Thanks for the help!