First things first, I don't see why you wanna ADD distortion to the Flextone HD.
If you set it to the Soldano SLO model, it has SO MUCH GAIN it will rip your head off.
I just had to delete a big section here, cuz I re-checked the HD manual at Line6.com. *The HD only has 16 amp models - the ones you see on the knob are the ones you get. *With the Pod & Flextone II amps, you get 32 amp models, and the new Rectified #2 model is WAY better than the default Rectifed model which your HD has. *Additionally, the version 2 software is smoother overall and switches much more nicely. *This is the main reason I didn't get the Flextone HD which was blowing out for $500 at GC recently...
The Flextone HD only has a MIDI OUT jack for switching other effects. *There is no way to hook it to a computer to to the tone dumps like you can with other Line 6 gear.
Also, are you using the Floorboard with your HD?
There are additional settings which are easily attained with the Floorboard -- an actual "DISTORTION" button which boosts the signal before it goes into the pre-amp like a stomp box, an EQ boost which sweetens the mids, & a volume boost for solos.
These are all selectable via TAP TEMPO + a control, as well. *Get the manual from the line 6 website if you don't already have it.
If you do already have it, READ THE THING cuz it's full of answers to the very questions you are asking.
As for how it compares to the real thing -- It's not a Mesa. *But it's close. *Especially for the money paid. *Add in the ease of use & the versatility of the floorboard and I wouldn't trade the Line 6 stuff for a real one. *(unless maybe you included a
volume pedal, a Vox wah, a tuner, a half-decent delay/reverb, a JC-120 for clean stuff, and a bradshaw switcher, too)
As for recommended settings to try, it really depends on what you're looking for. *For big distortion, dial up the Rectified model and set the following:
Gain - 9 or 10 (if it's too flabby, back it off a little)
Low - 4 or 5 (maybe more, cuz I'm used to the Rectified #2 model which has a ton of low end...)
Mid - 6 or 7 (crank this up to bring out the sizzle - the Rectifier model is pretty scooped-sounding naturally so you WANT to have some midrange added here. *If you scoop this all the way out it will sound flat and dead.
High - 7 or 8 (less if you have a trebly
speaker cab)
Also, dial in the DISTORTION (tap tempo plus turn the GAIN up past 12 o'clock) and the Presence (tap tempo + treble), if it's available.
