ah - gotcha. true, even in some old buildings in the US, some circuits haven't incorporated the ground lugs which can cause noise problems if you plug pro audio equipment into it. i find this the norm in flats and houses built before the 60s. in some cities like Boston, Chicago, NY and DC, unless the code requires you to update your electrical system, people usually leave them as is which can be bad if you collaborate with someone living in an old place but you make do anyways.
so i guess you were talking more in terms of an M-Box type of thing? yeah, the pres on those aren't bad but most people eventually upgrade to a standalone pre as their next major upgrade. as far as using outboard pres, i would suggest keeping the signal chain as spartan as possible using only the bare necessities to get a nice take down on disk. you shouldn't need an outboard EQ if your signal and take sounds good but for stuff like drum tracks, using a compressor before piping into the DAW might be a good option. however, using outboard pres these days isn't really as much a normal thing as it used to be because people are increasingly using in-th-box methodology when EQing and mixing unless they really want that extra special flavor from a specific piece of gear.
so to answer your question, i would weigh the trade-off with the noise factor and see if i still really want to use the outboard gear. if the sound is really THAT good then i'd say f%$ck it and just use the external boxes to spice things up a bit.
anyone else have a different take on this?