Room effects could be significant, and I would certainly play around with both speaker placement and listening position.
However, it may simply be that the S400's presentation is not for you:
The thing with speakers is that they all stamp their character on the sound, far more than any other component. For me it was a revelation when I once did a mamoth auditioning of 10 or 12 speakers, all in the same price bracket (equivalent to maybe around £2.5k today). Most were the top of the different manufacturers' ranges, and at the time represented a quite elevated level in hifi hierarchy, so I expected near perfection (!) - yet I was astonished to find huge differences in sound, so much so that with the exception of 2 or 3 the rest were abandoned as quite unsuitable within just a few (awful sounding) minutes. It brought home to me how very far from perfection speakers are as transducers that theoretically should convert the electrical signal into an exact acoustic replica.
I would never buy speakers based on just a review, unless, just possibly, I had experience of hearing other speakers reviewd by the same person and found that I agreed with everything s/he said, or unless I was sure I could easily move them on at no loss if I was less than enthralled by them.