increase your speaker distance from the front wall, if you can, and also remove items from in between the speakers, like equipment stands or TV's, if you can.
if you can make those modifications in speaker placement to your system and it still doesn't work, then perhaps it is time to purchase a new pair speakers or amplifier. you would be very surprised how much an amplifier can affect the sense of soundstage depth. if you do not have the ability to adjust your speaker placement due to other room-use constraints, then you are forced to compromise your system and shouldn't expect to achieve optimum performance from your system.
if you can make those modifications in speaker placement to your system and it still doesn't work, then perhaps it is time to purchase a new pair speakers or amplifier. you would be very surprised how much an amplifier can affect the sense of soundstage depth. if you do not have the ability to adjust your speaker placement due to other room-use constraints, then you are forced to compromise your system and shouldn't expect to achieve optimum performance from your system.