We do it inside the computer. When we used to use a DAT before the computer got fast enough we'd bounce to DAT without processing, copy the thing back into the computer and do it all in soundforge.

The UltraMaximizer is actually just a fancy hard limiter turning down any excess peaks in the music without adding too much distortion. If you hit normalize in an audio editor without running this kind of processor you'll usually find that it doesn't look anything like as loud as it could and there'll be a few little peaks that if they were leveled off a bit wouldn't make much difference to the sound but would let you get a good wack more volume out of the thing. A clever mastering limiter will sort these out without adding too much colour.

If you are mastering pop or something for CD mastering engineers or whoever will push these things quite hard for extra volume sometimes, but if you are going to cut some vinyl I reckon keep it backed off to just deal with any real excess levels.