NAD CD player won't play in NAD 3020 amp

Hello all - This is my first time on here, a Google search found you. I am not what you would call a professional audiophile at all so please speak in idiot speak. I have a NAD 5325 CD player I bought for $10 at Goodwill. My girlfriend recently bought me a NAD 3020 amp for my birthday, just like the one I used to have years ago and loved. My Technics SL1200 turntable sounds amazing through it, as does my Onkyo R1 cassette deck, but when I play my NAD CD player through either the auxiliary or tuner settings on the 3020 it sounds odd. There is no setting for CD on the front plate. This is an old amplifier. When I play a CD there is no vocal, and barely any music, just a wash of reverb, as though the song was playing at the other end of a long tunnel. A professional sound engineer pal of mine said I should switch the speaker cables around but that didn't work. I've tried all combinations of this and nothing brings the vocal in. What is going on please? I've never heard the like of this before. Thanks all.