I can't speak for the Rothwell's but I tried the Harrison RCA's not long ago. I had high hopes, as my DAC is far too hot for my amplifier and I can rarely turn the volume past 9 o'clock with all source data maximized. The great Alan Shaw of Harbeth (no less) had prescribed attenuators such as these as the ideal solution to such problems. I bought 2 x 12 dbl attenuators for each RCA cable, to try various levels.
The bottom line is that they absolutely killed the sound quality. The medicine was much, much worse than the illness, in this case. They went back a week later with zero regrets. Much better results for me just applying some DAC digital volume control and reducing the volume slightly through Roon. People worry about losing a few bits but it's negligible compared to the attenuators I tried. At least, that was my experience.
The bottom line is that they absolutely killed the sound quality. The medicine was much, much worse than the illness, in this case. They went back a week later with zero regrets. Much better results for me just applying some DAC digital volume control and reducing the volume slightly through Roon. People worry about losing a few bits but it's negligible compared to the attenuators I tried. At least, that was my experience.