Audio_sm - I'd be very hesitant to try to drive the Thiels from a Marantz receiver, regardless of the ratings. I have no hands on experience with the Thiels, but they universally are said to need power / current. My experience with larger Dynaudios, which also like power and current, is that you don't even come close to the full potential until you feed them right. I was driving them with 100 w/ch Krell KAV-series and then went to the 250 w/ch two-channel amp. Even though I rarely listen above modest levels, the speakers REALLY opened up. I believe you'll find the same thing with the Thiels.
If you like the Thiels sound, there's no doubt in my mind that they're worth the extra money if you can do the amplification properly - it's a whole different level. Don't take my comments wrong, though - everyone has budget concerns, so the fact that the Thiels are more demanding upstream doesn't mean that you won't enjoy them even if you can't do it all at once. I'm just saying that, if you buy them, you need an ongoing plan to improve upstream, especially the amplification. -Kirk