i usually get about 8-11, it depends on the plugs you use. there is charts on ua's website that break the plug-in's power usage down...(
link) hell, if you use the neve 33609, you get one instance

lot's of people laugh at how un-cpu-friendly the plugs can be, so if you are looking for bang for the buck, it's not uad. if you would like nice sounding emulations of gear you prolly won't ever own/use, uad is good for you. i like having an extra bit of power, or when i can't get the sound i want with live. fuck, in total, with an xpander and an uad-1, plus around 10 of the paid for plugs, i've paid less than my nice hardware compressor, which is mono, can only be used one at a time, and doesn't feature recall... look at it this way, soon they will release the
el7 fatso plug. an xpander, with it's voucher, could get you an amazing (hopefully) recreation of a box that costs $2k+, for $800. more flexibility, plus the
other plugs... shit. done.
but in the end, they
are just
tools. there are many other viable options, this is just how i feel about it.