Nick,

You have done an admirably rigurous work here, compiling data, thanks.

However for anyone reading this, it must be clear that unless VERY handy with a/screwdriver b/soldering iron and c/multimeter, better let this things to the DIYer or technical people. Even one-box solutions will need some thinkering and adjustement.

Then, when you are into DIY and brave enough to do this (PS replacement - upgrade), you know there are alternative ways to just replace one box (original SMPS) for another (alternative one-box LPS).

For example, and this will be my path (some day), I will use some of the boards I linked with separate transformer(s) and thus may distribute parts inside the M box. In the 861 there is much space, but in other units this may be the only way.

Or, as GGA pointed above, get rid of the PS (or just the transformer) inside the M unit and do an external PS.

As for the specs, space permitting, the higher rating the better (ask Naim users how the sound of their gear changes with 'overkill' PSs). Will not go with anything under 60W (4x required) but you need to look at the individual current capacity: most commercial PS have powerful +5 lines and weak -12 ones because they are computer oriented, and we have a different requirement here.

If you investigate a bit further the circuits you will understand why the +12V line needs to be good, and has such a (relative) heavy load: because many local regulators use this line to provide +5V to their local chips.

I have nothing opened here but from memory most modern M gear is provided +5 directly only for some logical circuits, and all the audio-related ones working at +5 (such as DAC chips) have the supply from the +12V line with a local regulator. This explains why the 'analog audio' lines (+-12V for opamps and so on) use just around 3W each, and there are another 8W used on the +12V for this. And why the +5V line use just 1W.

The 'one box' commercial solutions you list are quite different (as I said, probably because computer-oriented) and have a high rated +5V line and comparatively weaker +12 and -12 lines. This is why I underline the recomendation to use a different, maybe less 'easy', but better, PS. Oh and the original M SMPS are like those too, ie, not optimal in my view for the way their gear is designed (in fact I DO like the general design very much!).

Sorry for the long post (and I hope not too technical... I try to write easy to understand with my poor english!).

Cheers,

Josep

Basement: Linn Sneaky DS, 568.2mm, ARS Sonum Gran Filarmonia, Ramallo Allegro.
Living Room: 602, Linn Akurate DSM, Hypex Nc400, B&W 802D.