IIIRC, I think Coleman uses the
DACT attenuator which is a stepped, series attenuator with a fairly high impedance.
This presents two possible problems:
1. Series attenuation: as you increase attenuation, you increase the amount of resistors in the signal path, which can lead to coloration of the signal.
2. High Impedance: a passive attenuator with a Hi-Z has a strong potential to fuck with (reduce) the high frequencies passing through it.
To get an idea of what such a device can do to your signal, try out
this calculator on the Mogami Website. Try an input value of 20000 Ohms, over 10 meters of cable. For output impedance (your attenuator) try a value of 25000 then 2500 and compare the graphs.
However, when compared to a rotary potentiometer like the cheaper boxes are using, the dact is going to perform better.
...But in a passive environment, a custom spec'd, lower impedance, Bridged T from Shallco will kick it's ass.
-- Gary