Hello people My first post - old geezer returning to gigging- I just bought a second hand Hartke 2000 head I have a 4 ohm 15" speaker and a 12" 8 ohm speaker The Hartke manual says "connect any 4,8,or 16 ohm speaker(s)". I would like to use both my speakers, but together the impedance would be below 4 ohms. Glad to know whether this would be possible. What the manual says suggests that its ok, but I'm not sure. Other info: the ouputs on the back of the amp are each labelled 8 ohms. also written on the back of the amp are wattage ratings at 4 and 8 ohms. Glad of any advice. Thanks.