Didn't say anything was wrong with the amp providing the same watts at 4 or 8 ohms but it's interesting because wattage nearly doubles into 4 ohms if sufficient current, so the 2270 must either have no high current at all which is not good for a 4 ohm load or deals with it in some other manner which I'd be interested in knowing.

And, keep in mind a vintage receiver may drive 4 ohms but there's not to say there isn't going to be consequences. Back in the day of "vintage" receivers I can't think of a 4 ohm speaker built. There could have been but the standard was definitely 8 ohms so no need for manufacturers to make 4 ohm stable receivers. Brands like HK and Onkyo did high current because they realized the improvement the design had on sound quality. There's a difference between what a receiver is designed for and what some are willing to subject it to.