I was a bit worried that this would degrade the sound quality as they are significantly cheaper than equivalent products from Shure and Audio-Technica. It turned out that my worries were unfounded and this product is one of those that "just works".
I use two of these to attenuate the signal 30 dB from my RME Babyface Pro FS to my overly sensitive Genelec 8010. No loss of quality or uneven stereo balance noted.