You have taken what I said completely out of context. What I was trying to say is that based on the two values you provided which was only the slew rate and the bandwidth, that by the equations the amp would become unstable at a specific voltage with one caveat (as addressed in the documents I linked) that designing the amp for peak voltage above that threshold maintains stability. I also linked the Spectral specification where they specify all three values - slew rate, bandwidth and peak voltage.
So, I never stated that your preamp would be unstable above 1.5Mhz and now better appreciating how you interpret these items, should I ever conversate with you again, I will endeavor to be far more specific to prevent any misunderstanding.
Peace on Earth and Good Will to All