SpeakerLink was originally developed to facilitate custom installation. Bob stated he was surprised to find that it sounded better too, probably because SpeakerLink employs a balanced digital topology. I don't think any Hitchhiker has done a comparison so we don't have any anecdotal information of the magnitude of the improvement. Since Bob has said they will not offer upgrades to existing speakers, it is surmised that the cost/benefit ratio of the improvement is not high. I think the more important improvement in the new speakers is the introduction of apodizing filters. There have been indications that there will be firmware updates to implement apodizing filters in existing speakers. Everyone is eagerly awaiting them.

561, DSP5500s, DSP5000C, analog sides and rears