Galanti / GEM Super Deluxe 20 ('60) need help overhauling

[guile]

I found a hidden treasure the other day: an Italian Galanti / GEM Super Deluxe 20 from the sixties. It sound great. Lot's of sag, very warm and jazzy; impossible to make it sound harsh.

Here's what I did so far:
- I changed the existing speaker for a JBL K-120.

- I changed some of the tubes: 2 x EL 84 and 2 x ECC 83. The rest is still to come, but they work fine for the moment.

Exisiting tubes (I think):
2 x EL 84, 2 x ECC 83, 1 x ECC 81 (as inverter), 1 x Ez 81, 1 x 6DR7 (for vibrato)

- Next to the on/off switch there is a switch called 'antihum'. The mains ground wire was soldered to it for reasons that must have been important 50 years ago. I soldered the ground wire to the chassis to be sure.


There's almost nothing on the www about this amp (http://www.guitarmaniacs.de/cgi-bin/gal ... ry&id=4406)

Please let me know.
Thanks in advance.