I'm now left with one question and would like your advice/opinion - which will sound better 602CDT or 596DVD/CDP?

Meridian say any 500 CDT will sound better but some experienced user say the 602 can still sounds better. Now I understand that with the 508, 588, 596 and 598 there is the consideration that they use a ROM drive with less read errors so in theory they should definitely sound better.

What do you think?

My experience is...
The 601 makes my Panasonic 3D Bluray palyer connected via optical lead sound just as good as the 596 connected with a 75ohm RCA coax lead. I can't tell the difference and I was expecting the 596 to sound a great deal better. It's been explained that the 601/518/618 has buffers that eliminates most of the standard issues which makes any reasonable quality transport sound similar.

Keep in mind that the 601 is limited to 16bit @44Khz.

Meridian 601 DSP/Pre, 557 power amp, 596 CD/DVD + KEF Reference 105/3
iPad + iPod both with Spotify Premium + aptX Lossles Bluetooth receiver