Congratulations on your new Accuphase, the E530 is a jewel.
Beeing a Class A design it will run hotter than a class AB design like the E408.
Concerning your new speaker dilemma I will give you my opinion. SF are one of the most coloured speakers, some like it that way, some dont; Proac allways had a strange treble for me and never seemed easy to install in a room (never heard the D38).
The JM lab Diva Be is a good speaker and it might work with your system. For this price point there are numerous models that are worth an audition, try hearing the Audio Physics Avanti III and the Marten Design Miles II.