I've gone from (seperates that were part of my 2nd system): NAD C355BEE integrated amp, Arcam CD72 CDP, Monitor Audio RX2 speakers to the Marantz CR603 and it's been a superb move
One reason is that I wanted to reduce box count; the other reason was space (I want more back) and I've got it.
Having demo'd the Marantz with the Arcam Solo Mini and the Arcam Solo; for the price and IMO it's unbeatable
The wifi/airplay options are brilliant; the sound quality is superb with bags of punchy, deep and well timbed bass, smooth/detailed midrange and superb highs
IMO you'd have to spend close to £1k on an amp and CDP to get a good a sound quality as the Marantz offers and then obviously you'd have to fork out for speakers then too...
TBH the CD player on my Marantz has hardly been used; it's all internet radio and iTunes/iTunes radio via AirPlay