I am considering buying a 1957 Fender Bassman with the (5E6) circuit. I was wondering what the tonal differences are in between this circuit and the later 5F6 circuit that came the following years. I know the 5F6 circuit that the 1959 and 1960 models had is the most desirable, but they are also 12K. I can pick this 57' up for 3k. Is there any love for the 5E6 circuit from anyone that has had experience with them? Thanks in advance!