I think the transparaency is there in the price and the design. The LS50s are an £800 mini monitor designed to give high resolution performance, whilst the Marantz is a £350 amp designed to do as much as possible - D/A conversion, tone controls, phono input, switching for two pairs of speakers, headphone output etc. The Marantz is fine within its limits and used with similarly priced speakers but it won't power more difficult speakers as well as something where the investment is either larger OR more focused.
I originally heard Dynaudio DM2/6s a couple of years ago when I had a PM6003. I didn't like them (or so I thought). I then heard them again with the Arcam A18 when I had that and again I felt the same. Soft, slightly diffuse sounding and quite flat tonally. Something made me try them again when I got the Exposure and the difference is quite startling and taught me an important lesson. The Exposure is not a terrifyingly expensive amp but it is much simpler in design than the Marantz or Arcam and the investment has been focused on the elements that really matter. All the extra features have been stripped out but the highest quality components required to amplify the signal and control the speakers have been specified (within what is possible at the price). The 1010 makes the Dyns sing at a wide range of volumes (including, at this very moment, very low levels). They sound open but have good weight to the sound and voices and instrumental timbres have a tangibility I've been yearning for. I love listening to my music now and it is all through a loudspeaker design I twice rejected, a rejection I now understand was down to the inadequacy of the amplification.