Listen for yourself with a high power, high damping amp like the JRDG Continuum. If your favorite music has lots of bass, then there'll be a big difference.
Also, if you listen to the Sonus and they sound edgy, it's usually due to the set up. Sumiko dealers (Sumiko distributes the SFs) should know how to set them up properly, but for some strange reason most don't. If they're sounding edgy, INSIST that the dealer set them according to the Sumiko Master Set and come back another day to listen to them properly set up. Don't think you need to tone down the highs with tubes until you hear them properly set up.
Yes, they'll sound good with almost any amp over 100 wpc, but they'll really dance with about 500 watts. (Listen to the control of the bass).
Dave