Yeah the Roland AIRA modules are best used standalone outside of the rack. There’s a bunch of distortions out there though, that can be smaller, though the probably don’t have all the features the Torcido has.
A couple that come to mind:
- Zvex Fuzzfactory. The classic fuzz pedal in module format. Great if you want a bit of a Trent Reznor type of sound
- IDOW BatteyAcid, it’s a nice distortion module with compressor. A bit big to be honest, but you can use the distortion and compressor separately. It was made for the I Dream of Wires crowdfunding, but you can probably still find some on the used market
- WMD TRSHMSTR. Never used it, but the combo of distortion and BP filter might be pretty cool for some sounds
These are just a couple from the top of my head.
There’s several multi-fx modules that have distortion on board, like for example the Pico DSP from Erica. That’s great if you’re ok with more “static” effect processing
Also you can create distortion and overdrive effects with many VCAs. I find Mutable Instruments’ Veils to be a great sounding overdrive if you turn the curve towards exponential and set the right amount of amplification. Warps can also be used to create some interesting distortion like effect. Not all VCAs sound the same. Some actually can sound pretty nasty when overdriven.
Last but not least you can also use a rectifier (like the ones in Kinks) for different types of distortion effects.