Thanks Dave, I'm out of NE5532's and Maplin were out of stock too and didn't know when they'd be back in
So I'll get some from RS.
The only thing that are getting hot are the two 16V zeners (D11/12), but they do get hot in service, no?. The 3 other 0.33R's are intact
'U5' isn't getting warm, nor are any of the other opamps, at least in the short term, I dont like leaving it on in case something pops, although the amp is running through a 60W lamp limiter. Incidentally, if I connect an 8R dummy load to the o/p the DC offset swings to 7V!
As I say in post#9, the opamps run from an external supply seem ok, doesn't that preclude U5 being at fault?
EDIT: I just checked the 0.33R (R74) that I subbed and I read 125mV across it, the other 3 read 24mV, the schematic says to set the bias to get 15mV to 20mV.. The 16V zeners are definitely the source of the burning smell, they aren't happy!