I had attenuated interconnects from RA and used them between an Arcam CD62 and Rega Mira. They do give a better sound at lower volumes in that you have a better range of volume that you can use. Very low volume sounds lifeless and you need to up the volume until life is breathed into the music. With the attenuated cables I found that that point of life arriving, happened lower down the volume scale than before. But don't expect to hear a huge difference and to be able to use the whole range of your volume control. Also, don't expect the sound to improve (unless your previous interconnects were basic starter ones, in which case the RA ones use the excellent Kimber cable), the effect is purely on the range of volume that is useable.
The way to try is set the volume to the point that music sounds good, play a track, then swap to attenuated and play the same track without touching the volume control. It should sound louder.