Dennis, you probably know the answer to this as you are the only one who knows what kind of sound you like. These planar and dynamic speakers have very different sound quality. SL will not give you the macrodynamics/gut wrenching deep bass of the PD. The PD will not give you the inner detail/microdynamics of the SL. Soundstage/imaging is equally impressive for both but different. SL will sound more natural on acoustic music. The new Apogee Synergy at least on paper may be a good compromise of both.