Hi Nick,
and I've been told that they sound best into DSP8000

No, my point is that the 'power over SpeakerLink' connection may be seen as simply the easiest way of powering the MS200.
Owners may think that even if they have a SpeakerLink speaker designed to power the MS200, they would still get better performance using the external power supply.
Actually if using SpeakerLink speakers which can provide sufficient current for the MS200, like DSP3200 or M6 then you should use them to power the MS200 over the external power supply as the best performance solution.
Earlier SpeakerLink speakers may require the external power supply to provide robust MS200 operation, as they were manufactured before the MS200 was conceived, and therefore may not supply sufficient current for stable operation. A trial and error I'm afraid.
Cheers,
Rick