Cacophonix is a café au lait ('coffee with milk') poodle. This is a brown colour that is accompanied by a 'clearing' gene, and is the equivalent of blue on a brown base (blue is the same gene acting on a black base). If you have one copy of the gene, you are a café or blue. If you have no copies, you are brown or black, and if you have two copies, you are silver or silver beige.
When this boy is a year old, he will start to clear to his true colour, just like his father Loki. Loki has not finished clearing yet, so the longer parts of his coat are a mahogany colour, and the shorter parts on his rump and tail are more representative of the colour he should eventually be all over.
This is not the same as a coat that grizzles: the whole coat lightens and the effect is not caused by a buildup of streaky white hairs. Below is a picture of an 8-year-old holding brown with grizzle in her coat for comparison. Most blacks and browns will grizzle to a certain degree when they reach this age.
Café isn't an easy colour to photograph accurately or describe. 'Mink' I think comes the closest. It is a silvery colour, but it has a hint of almost lilac to it remaining from the brown.