systems seems to be playing slowly, need thoughts

I have a CJ12AL preamp, Onix CDP, and a 1980 vintage Denon amp. I had noticed recently I had a jitter type of sound. Last night I was listening to Christmas music, Johnny Mathis and his vocals had an oscillating, jittery, and drawn out sound. So last night I swapped out my Brimars and flipped in a set of Philips Heerlands thinking the tubes where bad. Anyway, listening to Tony Bennett tonight the same thing but the music actually sounded like it was dragging, playing slowly, which maybe causing the distortion. What does it sound like to you all? I'm thinking it may be the amp. Any thoughts or suggestions would be greatly appreciated. Thank much, Dave