A random source would be a very natural addition: Nano Rand, e.g. I also disagree with the first post to some extent. Though Maths is 20HP, it is such a multifunctional tool that it earns its keep even in a small space. I would, however, try to maximize efficiency where possible: the Mutable Shades or the Intellijel Triatt would you three channels of attenuation or mixing, which might be worth it instead of the A138, and the Mutable Peaks is a better use of HP space than the Dual ADSR since it gives you various kinds of envelopes, dual lfos, or drums depending on what mode you are in.