I want to buy SWR Goliath Jr. III cabs. My question is do I get two 4 ohm or two 8 ohm cabinets? I swear to you I have searched and read in the TB forums. I have done the same thing on the Internet (e.g., Harmony-Central, etc.). I can normally get my head around most concepts/ideas. BUT I still am not clear on this whole headroom/efficiency/ohm thingy. My situation is this: (i) I will be using an SWR SM-500 and the SWR Mini Mo; (ii) I have this notion that I want to run 2 cabinets in stereo; (iii) I definitely want a 2x10 configuration; (iv) I will be using my set up in non-professional settings (note there may be very good players present, but not playing for money); (v) I dont care about resale value; and (vi) its unlikely I will be playing anywhere or with anyone that would require anything more than moderate volume (i.e., small rehearsal rooms; coffee houses; small-mid size clubs, etc.). You would think it would be enough for me that the SM-500 manual says: When used in Stereo mode, the internal power amplifiers of the SM-500 will deliver 300 watts @ 2 ohms, 250 watts @ 4 ohms and 150 watts into 8 ohms. Optimum performance will be achieved by using a total of 4 ohms per channel. However, the lawyer side of me asks what SWR means by optimum performance. Does that mean the amps power, headroom, sound, and whatever else are all optimized by two 4 ohm cabs? If so, nuff said. But I dont see that definition anywhere and my reading finds players suggesting different approaches (i.e., 4 and 8). Hopefully, Ive given you enough to suggest whats best for my needs. Thanks.