The Rothwell Attenuators will change (lower) the load impedance his BAT VK5 preamp will see, and being tube it (the load) may come down too far for it to perform at it's optimum, and could roll of the bass early as it is capacitor coupled.
[url]http://www.stereophile.com/content/balanced-audio-technology-vk-5-preamplifier-vk-6075-power-amplifiers-vk-5-measurements[/url]
Cheers George
[url]http://www.stereophile.com/content/balanced-audio-technology-vk-5-preamplifier-vk-6075-power-amplifiers-vk-5-measurements[/url]
Cheers George