Shahinian Oblisk

Your question is a little unclear, but I'd guess the OHM setting you're referring to is on the amp. If so, determine from the manual or the website what the nominal impedence of your speaker (expressed in ohms) is, then use the speaker terminals from your amplifier with the same or a lower impedence value to hook up the speaker wires. In the case of the Shahinians, they have a nominal 6 ohm impedence, I'd suggest using the 4 ohm terminals.

Rcprince,

Yes, you are correct. The McIntosh amp has a choice of ohms level for connecting the speakers. I will go with your suggestion and use the 4 ohm terminals.
Can you explain what effect the a 2, 4, or 8 impedence has on the speakers? Does it have any influence on the reproduction of sound from your speakers? This is new to me. My old amp, a Bedini MK100 did not give me this choice. So I am hoping you can explain this to a novice like me. Thanks in advance.

Kgk, Rcprince is right on with the 4 ohm tap. The "OHM" is the resistance your speaker presents to your amp. By selecting the proper tap on the back of the Mcintosh, the amp will run in its most linear state. That's a good thing. If whatever speaker you use is between the 2,4 and 8 ohm taps, use the tap that is the lower of the two. Enjoy.

I'm no technical guy, but Onemug is right. A tube amp, other than an OTL (output transformerless) design, uses an output transformer to match its output with the impedence load your speaker presents. A solid state design generally does not use an output transformer and thus does not have different taps. The taps represent different points in the transformer windings (a transformer is wire wound around a core)that are optimal for the load in question. Outside of that I can't tell you too much, I'll leave it to a more technically inclined poster to correct me/elaborate for you.

By the way, I noted another post where you were asking about speakers to go with your new amp--don't be too anxious to change the Shahinians quite yet until you listen to them a while with the Mac, you might be able to resist the upgrade bug. The Shahinians are similar to my speaker system in terms of being closer to an omnidirectional speaker than the other, forward-firing designs you mentioned in your other post, and as such they present music in a significantly different manner than those other speakers. If you like and are accustomed to the Shahinian "sound", you might have trouble listening to more conventional designs. The other designs may do some things far better, such as pinpoint imaging and presentation of low level detail, but the overall listening experience might not be as pleasurable.

As others have said, you usually want to match the nominal impedence of the speakers to the output impedence tap of the amp, HOWEVER the real test is which output tap sounds best and it isn't always the "correct" one. Try both taps and see which one sounds better. You will not damage the amp or the speakers.