I don't think you can set a write offset in Feurio, so you should enter the combined read/write offset in the setting I've mentioned, I think.
The problem is that you can't enter a number of samples, only sectors.
So, if you had an offset of 650 samples, I'd enter an offset of 1 sector... If it was 1000 samples, I'd enter 2 sectors...
(588 samples=1 sector)
You can't be exact with Feurio.
I say that I don't bother because 1 sector = 13 thousands of a second, which is about the read offset of my Ultraplex. I will never hear that difference.
(And because it's difficult to find out the offsets

)
It really has importance if you make multi generation copies... the error would be accumulated.