Yamaha RN800a to Rotel RB1582 MK11

[Glenn Martino]

I purchased a Yamaha RN800a amplifier to use as a pre amp and i purchased a Rotel RB1582 MK11 to use as a power amp. I linked the two via the pre out RCA jacks on the rear of the Yamaha to the unbalanced RCA jacks on the rear of the Rotel and speaker wires out of the Rotel, switched them on at lowest volume and as i increased volume slowly it sounded horrible distortion. I tripple checked all connections, i removed the link between them and put speaker wires direct to Yamaha and sounded fine. Is the problem with the Rotel or is there a pre out setting that can be changed on the Yamaha?