I don't know if you have solved this, I see the thread is 4 months old. As everyone has suggested, room treatments make a very nice difference in taming top end or absorbing room nodes on bass. If you cannot do much treatment, I would suggest if possible to set these up in a triangle listening pattern, pull them out from the side walls as much as possible, then have the speakers at or near a full tow (pointing at you) when in your listening position. This will cut down on room interaction and with the speakers pointing at you rather than being capable of rebounding off glass will keep the top end from peaking so much.... next an amp/pre or integrated that doesn't have edge and is smooth will help a ton. For an amp, I would recommend a First Watt... one of the 25 watt models, maybe a J or newer or even one of its knock offs... pure class A, smooth and warm... then lastly a good inexpensive pre, I'm sure you'd get a ton of recommendations for a inexpensive tubed pre... I hope this helps,
Tim