Quote: Don't stack anything on top of a Valhalla---It's class A and get's hot . You should always put the hot amplifier at the top of a stack so it can get more direct exposure to air for cooling purposes. Stacking something on top of the amplifier restricts air flow, which makes the amp get even hotter, and it causes more heat to go into the component above it, which will unnecessarily heat up the other component and shorten it's lifespan. Cheers P.S. The active filter stage in the Modi means that it is no problem to hide it behind your computer (out of sight!) and run longer cables to the amp. This is Schiit's advice. That way, if you don't need S/PDIF or coax inputs, don't need 192kHz output, don't need the extra 3 years of warranty, or don't need to prop your valhalla up on top of a DAC, then you can save yourself the $450 on a Bifrost and just use the modi. Just don't stack anything on top of a really hot amplifier.