I believe the wide range of reported successes and failures of passive attenuation is based on the many variations in matching sources and amplifiers. Arthur Salvatore writes about this on his website (Link:http://www.high-endaudio.com/RC-Linestages.html#Int) and summarizes with;
Regarding digital volume control, here is an interesting paper by Daniel Weiss;
http://www.weiss-highend.ch/computerplayback/Digital_Level_Control.pdf
In short, if you need an active line stage because your source is not up to the task of driving the amplifier(s), then...
Any good active line stage, from any era, will improve the sonics in some obvious and clear manner.
Alternatively, if your source is up to the task of driving your amp(s), then...
No active line stage, no matter how good it is, will ever equal the sonics of your direct connection (or an equivalent passive).
Regarding digital volume control, here is an interesting paper by Daniel Weiss;
http://www.weiss-highend.ch/computerplayback/Digital_Level_Control.pdf