I don't know much about the Dynaco's but I do know the Heresy's(I,II,III)do not dip down much below 60hz. May I suggest a pair of Forte's(I or II). With them you get great dynamics, match well with tubes, vintage look, and used prices from $400.00 to $600.00. They also have nice bass down to the low 30hz.
Bill
Bill