I certainly do NOT consider audible hiss from four feet acceptible -- regardless of speaker efficiency.

I used to have a $400 JVC receiver, circa 1993. Infinity speakers, with a 104 db/watt sensitivty -- very very sensitive. Could I hear hiss from the tweeters. Yeah -- at about 2-3 inches.

My Rotel 1066 at 10 dB ABOVE ref level just starts to have audible hiss -- at a couple of inches from the speaker. I am using speakers with much lower effeciency now -- but hiss at FOUR FEET -- come on, that can't be reasonable.