There is much conflicting data out there, one place implies using a 4:1 balun, some a 1:1, and a few I stumbled across that said to direct feed it. I know there is not one perfect antenna for all bands, but the loop is the first one I have put up that would work (tune up) on most of them and seems to perform pretty well.
The plural of "anecdote" is not "data".
There are examples of people feeding loops many different ways, and I've probably tried
all of them (and a few more) over the years, but most of those are not accompanied with
actual data for the SWR curves, feedline losses, etc.
Typically a full wave horizontal is about 100 - 120 ohms or so on the fundamental, rising
on the higher resonances. While the 4 : 1 balun doesn't give a perfect match on 80m (a
quarter wave transformer of 75 ohm coax is better for single band use) it does give a very
usable SWR on multiple HF bands, much better than you will get with direct feed. SWR
may be high on 60m, 30m, and the upper half of 10m, but otherwise the losses should be
reasonable even on the bands where you still need a tuner.
And for those who say it is quieter, Can't prove it by me, just as noisy as the dipoles I have tried.
Noise is an electromagnetic radiation, just like desired signals, and any antenna picks up both.
But if someone is comparing it to an antenna without an effective balun that is picking
up RF noise as the feedline passes though the house, they might notice a difference.