From the Harmonix website:

Attach Harmonix room tuning devices to major surfaces of a sound room and the change is immediate. Instantly, the room offers a wider dynamic range with deeper silences between musical notes.

RFA78 room tuning devices

From the inventor Mr. Kiuchi:

Conventional tuning devices are designed either to absorb the reflected sound or totally damp vibrations of walls and ceilings. But, these devices take away the delicate musical nuances of the sound. Contrary to conventional room tuning devices, RFA78 lets the sound reflect freely, without distorting or masking the original information that the sound is carrying.

"These are mechanical devices, so it is difficult for me to unveil this technology to the public. Here is some basic technical background: I have been engaged in the Musical Instrument business for 30 years. During this period, we studied many famous musical instruments like Stradivarius, Guaneri and Amati to discover why they sound so good.

Finally, we came across one rule - that of controlling negative and positive relationship. It is a balance. We, as human beings, have decided that the negative part is no good. We concentrate exclusively on bringing the positive part into existence. But, the negative and positive relationship has to be equally balanced. This is balancing technology."

Balancing technology? Not much to go on unfortunately (and the explanation given appears contrary to my attempted reasoning). I'll ask Desart if I get the chance. 

Other than this I'm still sceptical (in the truest meaning of the word).

Now those Marigo vts dots. I do despair!

These helped to clean up the high end, allowing greater image specificity and an airier top end.