I have, and use, the Rothwell's to reduce the Cal Alpha's 3.5v output to match other sources. In this application I find it effective. The only down side is that it seems to slightly roll the high frequencies a tad, not necessarily a bad thing for the Alpha. I tried it between a pre-amp and amp and, as suggested by Rothwell, it did lower the pre-amps noise floor and give a better range of the volume control. Now the 'why', at least my speculation.....
The output of line stage of the pre-amp was 26v - the Alpha 3.5v. The effect of the insertion of the Rothwell (-10db), while constant, on the higher gain unit it was relatively 'less' and more difficult to detect.
It is also possible that a high level source might overdrive a pre-amp input and the use of an attenuator would reduce resultant distortion.
FWIW there are pre-amps with input gain reduction circuits (my SP 10 has a 6db switch on the front panel) which accomplish the same thing as an attenuator when used between the source and pre-amp. It provides a better range of volume control but doesn't reduce the noise floor.
I probably would not use an attenuator between the amp and pre-amp only because its an inellegant solution, not that its seriously flawed in any way.
Hope that helps a bit.
The output of line stage of the pre-amp was 26v - the Alpha 3.5v. The effect of the insertion of the Rothwell (-10db), while constant, on the higher gain unit it was relatively 'less' and more difficult to detect.
It is also possible that a high level source might overdrive a pre-amp input and the use of an attenuator would reduce resultant distortion.
FWIW there are pre-amps with input gain reduction circuits (my SP 10 has a 6db switch on the front panel) which accomplish the same thing as an attenuator when used between the source and pre-amp. It provides a better range of volume control but doesn't reduce the noise floor.
I probably would not use an attenuator between the amp and pre-amp only because its an inellegant solution, not that its seriously flawed in any way.
Hope that helps a bit.