Joe Peach wrote: the speakers seem to beg for more (or is it me?) volume. I don't want to harm the speakers in any way but, can I proceed to go higher. As I remember the Marantz is quite clean turned way up.

It is you, and its because of the very low distortion of the GoldenEar speakers. Low distortion speakers always beg for more volume because they don't "sound" loud even when they are loud. I'm going to guess at the loudest volume you listen to you 'd have to yell to be heard over them. That's actually quite loud and more power will only allow them to play a tiny bit louder (but probably considerably more dynamic).

As far as limits to your good old receiver, clipping distortion (overdriving the amplifier) is pretty easy to hear, and things will go from OK to bad in just a dB or two. You can find out where that is (just for a quick moment though), and use that as a reference of how loud the combination can't play. If you keep the volume just below this level you won't hurt anything. (Keep in mind I'm speaking of volume you HEAR, not the volume displayed on the receiver as that will vary depending on the input source.)