Reply to Trouble with new cd players... connection problems

I have Numark CDN77USB connected to ECLER NUO connected to BEHRINGER PMP 1280 but the sound sounds hollow and there's almost no high tones what could I be doing wrong?

Cd cables connected to high lines, ecler nuo connced with 2 RCA cables to 1 jack into the Behringer, Technics turntables connected to low lines of the ecler and they sound waaaay softer then the cd players