if an amp (even if played at painfully low volume - and we all know that every amp sucks with master at 0.1) annoys the neighbourhood, why should you but a smaller amp? of course a marshall mode four and a microcube operate at very different sound levels, but in a flat a modeler (hardware or software) seems the only logical choice to me... a POD or similar should let you practice and have fun at any hour and your neighbors would never even know that you exist!
no amp sounds even decent through headphones... go digital for home practicing and you'll never regret.