I have not found the schematics, I mean free!
but if you got some money to put in this:
http://cgi.ebay.ie/ws/eBayISAPI.dll?ViewItem&item=350119109094&translate=yes
but maybe a fellow member could provide you this... :
I seen that, maybe (so not sure), the mxp2000 is the little sister of the mxp3000...same design...but it could be totaly wrong!
so maybe it could help:
http://www.johnhardyco.com/pdf/MPC3000.pdf
http://www.fivefish.net/diy/sonyconsole/default.htm
BTW you can find on the links below some good PSU for this project.
http://fivefishstudios.com/index.php?option=com_content&task=view&id=42&Itemid=61
http://www.jlmaudio.com/JLM%20Power%20Supply.htm
je peux pas t'aider plus, je ne connais pas trop ces preamp!
bon courage!