Niles is usually very conservative with their ratings.

The heat sinks used in the Niles 1230 amp are MASSIVE. They do have 4 LM3886 chips per heat sink (there are Three heat sinks and 12 chips in this beast). The limiting factor is probably the power transformer. It's a toroid type with 6 42vct windings. There are 6 pcb's each having two LM3886 chips, a bridge rectifier and two 10,000uf x 35v caps for the power supply. The amp is built as 6 stereo channels, but each stereo channel can be bridged for use as a single channel with 80w into 8 ohms. I'm guessing that the VA rating of the transformer is between 500-800 from it's size and weight compared with other known transformers.

I have an old Sony receiver that I've taken apart. I'll probably build a three channel amp into it's chassis (each amp channel having two chips bridged). The heat sink that was used in this amp should be big enough with a little help from some small fans.