Get rid of excessive low bass

I am using Energy floorstand speaker in 4mx4m room and it produce woo sound in low frequency. Any interconnect cable can improve it? or do you have other suggestion?
Totally square rooms are a bitch for speaker setup. Before you invest any money, I suggest you try moving the speakers around and listen, get them away from corners especially. Sometimes only a few inches can help. Good luck!
Detlof is right. A square room is likely to give you terrible standing waves. You might try firing the speakers in a diagonal fashion. Room treatment (bass traps will help), but a 4 meter room is going to give a bass boost around 43 Hz. Most room treatment doesn't work very well below 80 Hz. The only other alternative is to go to an active equalizer. Audiogoner's will accuse me of Heresy--but unless you can change the room's dimensions you need a notch filter around 43 Hz. If you can afford something like a TACT I hear they are excellent. If you can't, I would suggest a McIntosh EQ. Unfortunately, it is analog and in the signal path and will add noise--a small amount. The McIntosh EQ's are very good--but not perfect.
abstract7, no heresy charges here! :>) yure absolutely right - bass traps or system-equalization will be the simplest, most effective cure.

re: moving the speakers around - try off-setting the speakers a bit - i.e.: have the left speaker either closer, or farther from its nearest side-wall, than the right speaker... or, even cock the entire plane of the speakers - i.e.: have the speakers different distances from the rear-wall, even tho the speakers-to-listener triangle set-up remains the same.

try elevating the speakers a bit as well as trying angled off center placement as suggested above. I would also experiment with placing furniture (or other objects in the corners both at the floor and ceiling.
Just recently I have been playing around with cords and cheap ($500) powerline conditioners. During that experimentation I found some interesting things could happen
One: rum a really small cord to your amp... 18 gage or less, it will cut your low frequencies and make them seem thinner but clearer.and the rest of the material sounds cleaner. A balance between too lean and normal is just some experimenting away... even a section of narrow wire in the powercord line... The effect is as if before: a thick woolly rinocerous was in the room: add the skiny wire and the bass becomes unwooly, cleaner... more angular. And cheaper than to buy a crummy EQ box.
Also try padding up one side/corner with drapes, heavy throw pillows in the corner angles on the floor.
I have a Tact 2.0 digital processor and confirm that it does a magical job of cleaning up the bass response in a room. When I swith the unit to "bypass" the bottom end becomes unbearably boomy. It's hard to believe that in pre-Tact days I tolerated this sound. Another less expensive alternative would be to find a Legacy Steradian processor. It is a very specific kind of analog equalizer, being an analog bass notch made specifically to tame room boom. One is able to adjust the depth of the notch, I believe. And as far as using power cords to equalize a system... I won't argue with those who have had success, but it's rather Rube-Golberg-esque way to equalize a system, don'cha think? Why not address it using tools intended for the job (i.e., digital or analog equalizer)?
I kind of like the power cord/cable suggestion as they may be part of the problem, as well as the room. Many constantly upgrade cables to get the mids and highs (as well as the bass) just right. Why not try this approach in particular for low end problems as well? I have not listened to an analog equalizer in a system since the mid 70's, but if they have not been greatly improved they would tend to compress the sound much more than a typical cable, IMO. My experience with them aslo was that their sound character (compression) was less noticeable on 3 and 4 way speaker systems and more so on two way systems. I don't know why this was, but it seemed to be the rule of thumb. As far as equalizers go perhaps a 30hz filter would give better results by clearing up available power reserves to handle/control what is left. Now what are some "great" cables that have "no bass"? LOL.
The VansEvers Double Pandora power cord has tunable bass and mids works great for me.
Lifting the speakers off the floor is a great suggestion. Several companies make 6 inch stands.
Elizabeth, cutting down on the guage of your power cord will definetly thin your bass but will also increase the chance of having a fire in your home. It is not very wise to recommend a tweek of this nature. This is a very dangerous thing to try and the possible consequences could be dire. As an ex-firefighter, I have seen with my own two eyes what can happen as the result of overloaded outlets, underrated extention or power cords etc. Some of them were even fatal. I suggest you keep these type of suggestions to yourself.