The Fathom and V12 are literally designed to run at 2ohms, from my understanding... they actually have a 2ohm switch. The Big Block 750 is also designed to run at 2ohms, and does not put out its full power unless run at 2ohms (I believe the V12 actually puts out a touch less power into 2ohms than 4, if I remember correctly, and the Fathom/M6 puts out the same power into 4 or 2ohms). Many run the Walkabout and MPulse600 at 2ohms, despite recommendations against it (in the manuals for these units), with none reporting any issues that I remember. If you are planning on running 2ohms as your standard operating impedance, it seems the V12, the Fathom (now called the M6) or the BB would be the way to go, depending on your tone goals. Edit: The Genz750/1200 and CarvinB1500 also crank along just fine at 2ohms.