I run my non adjustable Weller with #7 = 700º tips and it works fine. I also use Cardas for Hi Fi, but used to use it professionally with aerospace boards and equipment, black boxes for aircraft for example, with standard 60/40 multicore with no problems. It was the standard we used. When you are a whizz and soldering all of the time doing the work with the control turned right up is probably fine but 700º gets the job done with a nice amount of control, especially with board work.