I just picked up an SVT head that I'm pretty sure is in the 1969 range. It has black rocker switches, two black toggle switches, there is an attached speaker cable, and the s/n is 100230. My question is that there isn't an impedance switch or anything to say what impedance it will be wanting to see in a cab. The attached speaker cable is for use with an SVT cab (with a DIN type connector like my fliptop B-18 had). There is an additional speaker output for a 1/4" connector. What impedance should my cabinet have for this amp - 2, 4 or 8 ohm? I would guess 4 ohm, but I want to know for sure before I hook it up to check the amp out. I haven't turned it on yet. Thanks!