hales transcendence 5 and mcintosh mc 300 advice.

can someone tell me what should be the best connection on my mc 300 with auto formers. 8 ohms or 4 ohms with the hales transcendence 5 speakers, i don't know what the nominal impedance of these speakers i just got them used and can't get that answer. it seems i get more bass when i plug them in 8 ohms but is it the best way or if they are 4 ohms speakers i should connect them to the 4 ohms on the mc 300 since there is that choice, thank you for your help with that.
When I last talked to tech. support from McIntosh, I wasn't sure what the impedance was on my speakers either. And what the tech guy told me was to hook it up to the lowest ohms available, in this case, 4 ohms. Macs are autoforms any ways, so don't worry about doing any damge to the speakers or not providing enough juice to the speakers. If I'm not mistaken, all Hales are rated at 6 ohms.
Just my 2 cents,
Actually, you can hook it up to whichever tap you like better. You won't damage anything either way. You are right - the sound does change when going to a different tap. The lowest one available will give you the least distortion (on paper) so that is what they will tell you to use but you don't have to. Try them both and pic the one you like best! Arthur
thank you for your help evrybody...