I was thinking about that, but not sure how affordable it would be - it needs a lot of good quality iron.... Love your idea about EL509 - I have few PL519 that are waiting to go into a one-off custom work....
This model from Radii looks promising - knowing their designs, it should work very well right out of the box, and build is such that modifications are very easy:
http://www.radaudio.com/alm135.htmlBeing their distributor in the US, I'm little ashamed that I don't know the price off the top of my head, will need to check when I get back home....