Comparing HK 3480 to 3485?

Does anyone know how the power amp section alone (not whole receiver) of the hk3480 compares to the 3485? This question is really addressed to two-channel. I've got a 3490 and a 3485. The specs are about the same, but the 3485 sounds slightly better. Parts or arrangement of these parts is a little better in the 3485. I need a second 3485 and wonder if the 3480 would be comparable.