Hi Jake,
Many thanks for the reference to the link and I'm enjoying the EE Minimax dac bought from you previously immensely! It was actually reading this article that got me interested in the idea of op amp rolling in the first place and I've followed up on the sources of where to obtain. Wasn't sure however whether my electronics skills were up to the task of replacing these however from what I've since been advised, it seems not to be too demanding therefore will probably look to replace myself. Unless someone more famiiliar would not take the risk and employ an expert to get this work done!
Best,
Vince.