Ok, the series resistance that goes to the LED is designed to put down voltage from 24VDC, so maybe it’s quite heavy since now there are +9V, anyway this is actually working and the hum has absolutely gone, this was my very goal!

Just a consideration about supply, now I have not really 9V but +10-11VDC from PSU, I read 4558 datasheet and this shouldn’t be a problem, right?
http://focus.ti.com/lit/ds/symlink/rc4558.pdf
18V is the max voltage, I’m about on 10V.

Thanks for your help.

Now, another to-do-mod should be the TB with a 3PDT, this should be “easy”

After rectification I’ve got 24VDC.

I mean, it should be right that 4558 is powered with +9V, but this is just a leg of the circuit, I’ve got a lot of thing connected on the main leg at 24V, so I think the best way to convert the factory AC/DC is powering with 24VDC in the exact point where rectifiers end, then you’ll have 9V on 4558 and 24V in the other places where needed, as original factory!

Anyway I’ll work this out deeper in the next few days.

Actually I’m running at 9V where it was at 24V and it works, but I’ve got some strange behavior with volume that waves (this was my impression), maybe can be related with gain undervolting.

Hey guys this should be absolutely nice and interesting.
Any help? I’ve got the same exact problem.

Mine is the “european” version 220/230V AC powered, I attach a photo.

How easy could it be converted?