Congrats! I'm kinda looking into an Engl myself. What's the difference between the Savage and Invader?
Since I own both, lemme chime in.
As others said, Invader has 4 individual channels with a low and high gain mode for each. 2 Master volumes (handy for leads) and overall Presence and Depth controls.
Channel 3 has the Engl rhythm tone goods. Channel 1 is beautiful chimey clean that stays really clean in low gain more and high gain mode adds some grit, low crunch.
Channel 2 is a smoother take on Marshall-y tones. It's less raw and thicker. Goes from classic rock gain up to modded, hotrodded 800's, but while the gain range it spans is near perfect, it lacks some 'kerrang'.
Channel 4 is a true lead channel, but IMO the most lackluster; too saturated and wooly thick. It's too much Santana and not enough of what made Engl famous in the first place.
Now, the Savage 60 (MKI) is more bare bones, a bit more dry and a lot rawer sounding, with still a lot of saturation.
As its a simpler amp than the one
@JerEvil has, it's 2 channels with shared EQ, individual presence knobs (very handy!) and Depth Boost switches and while it has a gain knob per channel, the rhythm channels' gain affects the lead channel. And there are switches per channel for a gain boost, unfortunately not footswitchable.
Individual channel volumes and a master volume.
The cool thing is, because of those interactive gains, you can set it up for a lot of duties. Really clean + 80s lead tones, Malcolm and Angus, JCM800ish and high gain tight Marshall... All possible.