@immatthewj, sure. If gain issues exist in the system (in my case, due to relatively high voltage output of the upstream DAC), this results in my using the downstream volume pot (of the headphone amplifier/preamplifier being fed signal from the DAC) rotated nearly all the way counterclockwise. That means if I rotate that pot very far at all in the clockwise direction--to increase volume--the already borderline-excessive volume increases quickly and to an intolerable level.
Traditional wiper-type volume pots often exhibit sonic nonlinearity at this extreme counterclockwise rotation. Typically this is experienced as poor channel tracking, with one channel sounding louder than the other. Depending on the specific volume pot, there also might be higher than usual audio distortion at extreme counterclockwise settings.
One goal of reducing system gain via devices such as the Rothwell attenuators (installed in the RCA inputs of the amp/preamp) is to reclaim some of the lower roatitonal range of the amp/preamp’s volume pot, so I can adjusting the desired volume a little further up from the farthest counterclockwise position, thus avoiding any non-linearity at that position.
Note: with certain other types of volume pots (ie, stepped, reed-relay, or digital domain designs) there is no apparent non-linearity at the pot’s rotational extremes. Thus these pots exhibit little or no nonlinearity with in systems with excessive gain, Howeverr, there may still remain the issue of having "too few steps" for effective volume adjustment.