Hi guys, sorry for my late response!
The PowerStage 170 looks killer, but it's really expensive.. But maybe it's worth to invest in something solid, if I have to pay more than 100€ anyways.
Okay, I'm getting the feeling that I misunderstood something then. What do you mean by "PowerAMP-Sim"? I put a FxLoop-Block before the Cab-Sim and went from the FXLoop-Out to the FX-In of my ENGL-AMP. Do I have to disable something else? I just want to use the ENGL to boost my signal without modifying the sound.
I uploaded a screenshot of my AX8-Edit: dropbox.com/s/3ov9nc2rv75basr/ax8edit.png?dl=0
Unfortunately with a tube power amp there is going to be some inherent tone coloration... It's part of why so many people are die hard fans of their tube amp of choice. The counter argument is that with the poweramp simulation on the axefx combined with a good solid state amp and the right tweaking you can just emulate any amp you want. But I digress.
To disable poweramp modeling you can either reduce the Sag parameter to 0 or go into the global settings and disable poweramp simulation there. Not sure if you know most of this already, but a guitar amp is broken down into a preamp and a poweramp. With a lot of modern high gain amps, most of the tone comes from the preamp and the poweramp is designed to be (mostly) loud and clean. With a lot of older amps, a lot of the tone that people seek after comes from cranking the amp until they start saturating/clipping the power section (tubes). This is why an amp like an old Marshall is so hard to use, because when you have it turned down to a level that doesn't kill you, you lose the magic.
So, by having poweramp Sims enabled and then running into a tube poweramp, you are basically doubling up on what should be happening... Emulation of power tubes and a transformer etc are being sent into real tubes and a real transformer etc. Sometimes this can work well and not seem off, other times it can cause problems in your tone that you spend ages trying to eq out when you really can't fix it with eq.
Try pulling up the Angle Severe (1 or 2, whichever sounds better to you off the bat, they are based on the Savage 120 with rough mode on/off.... Should be similar to your amp) and disable power amp Sims globally. Sounds like you're already bypassing the cab properly, but you can bypass the cab block and make sure it doesn't affect the tone just to be sure. Master volume in this setup shouldn't affect your actual tone, so set that to whatever for levels, and set the rest of the controls to taste. Go over to the speaker page and bring the LF resonance down to zero. That setting has a huge thread in Cliff's tech notes section, but basically for a tube poweramp you want it at zero for the same reasons I talked about above.
From there set your blackmore master volume for as loud as you want it, don't forget you can lower the level coming out of the ax8 in order to crank the master on the amp a little more if you want. If it were me I would start with whatever master volume level I would normally use with the amp by itself, then set the ax8 out level to match perceived volume. I used to own the Savage and if I remember right I never really had the master much higher than 9oclock, maybe 10 and that was house rattling loud. You should also try adjusting the engl's presence and resonance controls (if it has them) because they might still affect the tone.
I'm beat after a long day and typing on my phone, so hopefully this all makes sense and I didn't leave out any key info. I'm pretty confident you can get an absolutely killer tone out of the setup you have. Getting a nice SS poweramp is definitely a good goal, but if you can use what you have now so you can spend some time saving for the right amp you'll probably be happier in the end. My .02c.
Let me know how it goes, happy to keep up with the thread and see what we can't figure out for you. My setup was almost identical except I plugged my ax8 into an e840/50 and then into a Vader 2x12.
