I never heard of Cirrus, but there is DACT, Goldpoint, Elma, Shallco, Noble, Penny and Giles, and etc, all of which make excellent two-channel balanced attenuators in your choice of impedance. (I am sure I left out a few other quality brand names.) Depends upon how much you want to spend. In addition to conventional resistor-based attenuators, like those mentioned, you can also think about attenuators based on light intensity and a photo-electric cell. (I guess that is what danager points out above; I personally would stick with resistors.) No reason to mess with an 8-channel device when you only need 2. If you don't already know much about attenuators, you might want to spend some time familiarizing yourself with the pluses and minuses of the various types, e.g., series, shunt, or ladder type, and e.g., stepped attenuators vs continuous types, etc.