Does anyone know the diffrence between the Hartke Mosfet'3500 and the HA3500 ?? Do they have the same power supply,components ect. I played a 2004 HA3500 that had no sustain at all and then bought a Mosfet 3500 that sounded great with way more power and sustain.. Perhaps the older HA3500 is the same as the Mosfet??