Found this: http://www.dact.com/html/attenuators.html
could this be of some use?
I'm thinking of 8 balanced innputs (from adat) via maybe some ON/OFF switches to some kind of arrangement of these.
I once saw an active solution based on a chip named PGA-2311 (there may be newer versions) in Elector April 2004 in the 10 Euro range per channel
specs are 120 dB dynamic, 0.0004 % THD+N