Yamaha RX 870 - Interesting Design Decision

[wrat]

so my yamaha rx870 will NOT play straight quad recordings it will downmix to 2 channel or upmix to whatever but simply will not decode quad BUT will decode dts quad/dts hd quad for example
Clapton Gimme some strength has the original quad mix of "Theres one in every crowd" and "461 ocean blvd" I cant play well I can but they sound awful in 2 channel..
I can however play the new Doobie Brothers quadrio set no prob..