Yes it's true that you can use Aggregate Device to stack Firepods.
But Firepods only let you use one of the 2 or 3 as master clock.
No external clock input. SPDIF inputs are not functional with multiple
chained units.
Looks like it's Metric Halo 2882 or Alesis HD line inputs with extra
console pre amps/direct outputs or go crazy with TDM/PCMCIA and
outboard mic pre (not where I want to be going)...