My general experience is that even if two amps like the Power 1 & 2 are made to the same standards (and I am not sure if these two are exactly), the sound must inevitably change in more ways than that one simply offers more volume capability than the other. In fact, I would go as far as saying that more volume is not the primary purpose of offering higher-powered versions of lower-powered (and -priced) amps - rather, it would be more accurate to say that lower price is the primary reason for offering lower-powered versions of higher-powered amps. More power means things beyond simply more volume, and different circuit iterations and parts' quantitative ratings sound different, even if the circuits' basic topology and parts' qualitative ratings are the same.
I haven't heard these two amps, but I would expect them to sound similar, not the same, and would also assume that the degree of difference would partly depend on what speakers they are being asked to drive and how. But even if all other things were equal, I would normally expect the higher-power and -priced amp to sound better (though this is not a rule, and not always universally true). Hopefully someone will reply here with an opinion from comparitive experience, but I would also suggest contacting SF/Anthem with your question - since they no longer sell these amps, they have no proprietary interest in the answer other than to offer you advice based on the facts as they know them. No matter what their original advertising campaign said (and I don't remember the claim you refer to), I seriously doubt that the folks at SF who made and work on these amps would consider their sound quality to be identical.
