Hello all. I have a Hartke HA 7000 head. I want to replace the tube/s. The head has 2 - 350 watt amps in it. The manual does not go into what kind of tube/s this thing has. I just want to know what tubes it comes with (12ax7's ?) and how many. Also would like to know if other tubes (like a 5751 for instance) might give the amp a warmer feel? It's still a bit "harsh" for my tastes even when I have the solid state preamp all the way down and and only use the tube preamp. HELP!!!