Here are some quality remote controlled attenuators (the ubiquitous motorized Alps pot excluded) that can be added dto an active preamp.
http://www.tentlabs.com/Products/page31/page31.html
http://www.tubewizard.com/new_remote_volume_control_is_the.htm
http://www.marchandelec.com/att.html
(this one looks like the one used by Atma-sphere MP1)
http://bentaudio.com/index2.html
http://www.partsconnexion.com/tkd_73340.html
http://www.tentlabs.com/Products/page31/page31.html
http://www.tubewizard.com/new_remote_volume_control_is_the.htm
http://www.marchandelec.com/att.html
(this one looks like the one used by Atma-sphere MP1)
http://bentaudio.com/index2.html
http://www.partsconnexion.com/tkd_73340.html