Rookie Question, maybe

I’ve been playing around with the different outputs and come to the conclusion the it almost sounds like the speakers are working harder when hooked up to the 4ohm output.  8ohms it is until I decide that it isn’t.  Thanks for the tips!

I don't use the 4 or 8 ohm rating of the speaker to decide which tap to use. As a starting point, I check the impedance curve to see how demanding the load is. But that information isn't definitive.
In the end I find that listening to both taps will determine which sounds best.

I'm of the mind you should try all options and different ohm selections ,then pick the one that sounds the best ,there are no mandatory settings with that speaker .

Speakers ratings are always approximative, just look at any measured impedance curve.  They give a rough idea of how hard they might be to drive.  I doubt many amp's 4 and 8 ohm hook-ups are exact either.  The obvious thing is to start with 4 to 4, let the amp run in, get familiar with the sound, then change to 8 to see what differences you notice, and whether they're better or worse.

Welcome to Audiogon. You are going to find that you will get a variety of opinions on any topic or question you post. I consider that a good thing, but as you can see you already received two different answers that could have you going two different directions. Here is my advice: Read the Prologue manual (hard copy or online) to determine whether it specifically says you should not connect 4ohm speakers to anything other than the 4ohm posts. If it doesn't tell you to expressly avoid such connections, then I would try them all and see what sounds best to you. This is a hobby. As such, you should try different options when they are available unless they are patently dangerous, will void the warranty, or you're not sure if it will damage the equipment. I would be surprised if trying your speakers on all the optional speaker posts will hurt either your speakers or your Prologue.
Have fun
Al

It’s my understanding that the 4ohm and 8ohm Connections on the tube amp will allow safe power supply voltage for speaker load.  I think it’s based on different taps for the output transformer.  So, if you have 4ohm speak res, connect them to the 4ohm binding post on the amp.

Thanks.  I just want to make sure that I am not going any damage to either the speakers or the Amp, mostly the amp.

Try them all and use the ones that sound best to you.  There is no right or wrong.