From what I know, there are only a few people who have listened to the Grange...and those few have been very pleased (to say the least). From Mick, I've received mixed statements - on one hand he told me the Grange wasn't necessarily better than the Cortese, just different and on the other, he said the Grange was "the ultimate" and would "blow away the competition...if it has any".
My bet is that the Grange is a great preamp and at the price, it should be.
My bet is that the Grange is a great preamp and at the price, it should be.