Arkless Electronics
Trade: Amp design and repairs.
That link doesn't work but one in the "Audio" section does.
I think dropbox has changed, anyone can view via the above link on my Sept 17 post.
"You can share files with anyone, even non-Dropbox users, by getting a link to any file or folder. Once you get the link, you can send it by email, Facebook, Twitter, instant message, social networks, wherever you want. You can share these links with anyone, even if they don't have a Dropbox account."
There are schematics for the preamp PCBs as well as many others.
Let me know if the link does not work.