I built a Stereomour 2A3 integrated amplifier and originally upgraded both the interstage and the parafeed caps with Mundorf Silver/Oils. Since then I tried various capacitors including the Russian FT3 for the interstage cap (0.1 uf). I ended up with the Jupiter wax/copper foil and found it to be as extended in the highs and bass but fuller in the midrange. This was a clear improvement and was missing with the other caps.
I am wondering if replacing the 3.3 uf parafeed Mundorf with an Jupiter HT flat stack (the copper foil would be to expensive) would provide a similar benefit.