Here are a few things I would suggest as improvements to the Marshall Code series. I have a 25 so some things may be specific to that amp. I have stuck to things that could be improved only by software or firmware as these are improvements everyone can have simply by updating the firmware rather than modifying the amp itself.
1. Reduced power mode to switch between full power and lower power mode. This would fix the volume control issue everyone complains about. Maybe this could be a global setting in the firmware ?
2. USB audio Volume level setting (e.g. -3dB, 0dB, +3dB etc). This could also be a global setting in the firmware ?
2. Normalise the volumes of the models, some are way too hot (British class A power-amp), some are way too low (Natural pre-amp). I beleive this is the reason why some models have strange low frequency distortion (50s British, OD DSL).
3. Show the configuration of the Cab models, not everyone is a Marshall fanboy and I have no idea what cab a "1960X". even if it was displayed as "1960X (4x12)" I would at least know what the configuration of cab the model is.
4. Fix the spring and hall reverbs, they sound very cheap, like the "echo" you would get on a cheap karaoke machine, certainly nothing like a spring reverb.
5. For god's sake release an official desktop editor!!! with the option to save/restore/edit patches.
6. A sync button to sync the amp presets with your gateway. It you want to rearage the patches online in gateway, you have to manually save all the patches one at a time to the amp using the phone app. So if you add a new patch at position 0, you have to manually save all 100 patches one at a time in order to match your gateway sounds!
7. Fix the tuner, it is pretty bad on both the amp and the app. It's slow to respond and not very accurate (at least thats what its like on mine). Ive no idea how well it works on the foot controller.
8. If possible add a Fuzz pedal model, even at the expense of removing another model (I wouldnt miss the pretty poor Acoustic simulator for instance).
These are just some suggestions that I feel would make the amp just a little bit better, but in general I'm having a lot of fun with this little amp, and love the sounds and features it has. It is way better sounding than some of the negative reviews online would suggest.
Maybe other people can suggest firmware updates too?