Bought the HW-D450 on Saturday and very impressed so far for what it is. However in the first day noticed the telly having its source input randomly changed away from HDMI 1 a couple of times. Did a quick google search and found loads of similar complaints but all linked to the previous model. Read the manual a bit more and noticed I hadn't added the ferrite core to the sub. Not sure if it's just chance but not had any issues since added the ferrite core. Also note the the HW-C450 did not have them. Does this suggest this is the fix for the original C450 problem?