Hi Matsaly,
For the record, I upgraded the power supply on my Squeezebox Touch and did get a noticeable audible difference (however it was not so massive as installing the SBT Toolbox V3)

If you consider the SQ Touch to be Logitech's equivalent of an Sooloos "End Point" then maybe it is possible to improve the "End Point" sound of a MC200 with an upgraded supply. My guess is that the difference would not be great.

If you do try it, please let us know how it goes.

/Marcus

Lounge: 861v4+ID40 (hardwired Cat 6), HD621, 2xDSP6000.2VC (l/r), DSP5500.2HC, 2*Jamo ARTina (rears), D2500, 556, 596P, PS3, Humax HDR-1000S
Bed 2: MD600 (hardwired Cat 6) , QNAP 453 Pro