Also, you might try pointing the existing speakers back at the wall and going for a wider more expansive soundstage - think 901 but with much better quality. If you preamp has a mono , phase and reverse switch. I would also experiment a bit w that functionality.
you might also try more corner loading - trading spatial cues ( from reflection) for more bass output....
you might also try more corner loading - trading spatial cues ( from reflection) for more bass output....