Just uploaded a very quick live A/B switching test between Q10 and Q9.04
I am using an AX8 to A/B switch the signal into 2 x AXE FX IIs.
The AX8 preset uses 2 scenes to toggle an A/B output signal to either AXE FX II.
One unit has Quantum 10 (AXE FX II mkII - Bottom)
and the other unit has Quantum 9.04 (AXE FX II XL+ - Top)
The presets are identical in each unit. Nothing fancy either.
All controls are set to NOON - except for the USA IIC++ presets - as they require different EQing to sound "correct".
You can see the settings in the short screen grab i display before each demo.
The Cab is a wav IR loaded on the output bus within Cubase.
I did this to remove any chance of variation within the different firmwares CAB block.
This way we are looking at ONLY the tonal differences of the firmwares.
The CAB is a blend of a Mesa Recto w/ V30s, a Marshall w/ Greenbacks, and an Orange w/ V30s.
All Mic'd with multiple SM57s in a "Full Spectrum" configuration (IE, all points of the Speaker have been Mic'd and blended into a single IR)
Just to be finicky, there's still something that can influence the comparison: the input stage circuitry is slightly different between the mkII and the XL (different "secret sauce" version). If you've connected the ax8 to the rear inputs they should be identical though.