here are all of the options
1- new power cables - try shunyata viper only 100 bucks
2- new speakers cables - try regular radioshack cables
3- panels for sides and front wall - or heavy drapes on front wall
4- try hifi fuses on the speakers - I use them and love them
5- get a thick rug
6- make sure the sub is set properly sometimes its set to take the lows at too low a rate meaning have the sub only take on 40 and below pushing the lows to the speakers
7- change the size of the speakers in your denon - either from large to smallor or small to large
8- add a second sub
1- new power cables - try shunyata viper only 100 bucks
2- new speakers cables - try regular radioshack cables
3- panels for sides and front wall - or heavy drapes on front wall
4- try hifi fuses on the speakers - I use them and love them
5- get a thick rug
6- make sure the sub is set properly sometimes its set to take the lows at too low a rate meaning have the sub only take on 40 and below pushing the lows to the speakers
7- change the size of the speakers in your denon - either from large to smallor or small to large
8- add a second sub