I've had both of my K-IV Bass and Lead heads opened and there is not two 5065 boards in them. There is a single massive board. This is the later 400 watt version with the voicing control. I found this out the hard way while playing Bass one day. I had just paid a couple bills getting this cab rated at 300 watt reconed and it played four songs and quit. Smoke rolling out of the ports told me the whole story. I went to the web site to find there were two versions of that amp and the first ones were 270 watt and the later versions with voicing control were 300 or 400 watts. These later IV's are very serious amps and wont have mercy on under rated speakers. Steve C