Getting overtone in a pair of bookshelf speaker.

"To Mapman: will follow your prescription and see what happens. I am not sure about the usefulness of aiming the tweeters 2-3 ft to the side, but I will that a shot. "

The main thing is to at least try having them not fire directly at you, but to either side of "the sweet spot" where you listen, possibly with speakers far apart and out from rear wall and closer to side walls. That will affect the high end and upper mids maybe for the better. Then play with teh placement away from the walls so no early reflections and to get the soundstage and imaging tuned in. Asymmetrical placement may even be OK. Listen for "holography" in the sound with this kind of placement, sound seemingly disassociated with the actual location of the speakers. You will be relying on reflected sound heavily rather than direct sound in a more typical nearfield listening type setup. Its all good (when it works)!

This are some things I have found useful in similar situations with small monitors in smaller rooms. Its easy and cheap to tweak speaker placement and I would always attempt to get a handle on that before jumping ship on any particular pair of speakers. There are many other tweaks that might be worth a try also once the speaker placement issue is addressed.

"MoFI, the Marimbas have about 7 hours on them, so I am far from Nirvana"

You need to put a lot more time on your speakers before you even listen to them. With only 7 hours on them, you should be able to hear a noticable difference in how they sound every few hours. At 30 to 40 hours they should start to level off, but you need to put at least 100 hours on them before you judge anything. Use white of pink noise at moderate volumes if you can.

What kind of amp do you have?

Have you tried a little bit of single-malt Scotch?

TO ZB542, The amps are a pair Red Dragon digital monoblocks, and a Bel Canto PRe3 line stage. Speaker cable: Audio Art SC-5 (not special edition, that is the SE version)

1800 hours of break in will improve them..then you can go out and buy some good speakers!