Ah yes, I figured this humble post would bring out some folks! I agree: "No rules in this game." It's all about synergy and matching a system to fit what sounds best to your own ears, IMHO.
Like I said, I thoroughly enjoyed the SP100s for several years with the Mac gear. Ditto the 1/2s. But I listen to mostly classical, acoustic, jazz, folk -- the very music that Spendor Classics are especially adept at presenting in such a fashion that it melts the soul with its beauty. Were I a huge fan of Led Zeplin cranked to rattle the windows, I'd have different speakers.
IMHO, if you're passionate about your Spendor Classic (or Harbeth) and you haven't tried a really good small tube amp, borrow one. Then give your ears a day or two to adjust to the sound. It could be right for you. It was for me.