As for a good source of loopable ADs in a smaller space, have a look at the Intellijel Quadra. Four envelopes, linear or exponential curve, either AD, AR or looping. And as far as VCAs in a tight space go, see what Happy Nerding has with their 3x VCA...it's quite a nifty thing, with three DC-coupled VCAs with some switch-configurable mixing abilities. And with that at 6 hp and 12 for the Quadra, you've still got 2 hp to jam something else in, so...bonus!