I'm going to commit heresy and recommend a solid-state amp. Don't get me wrong, I'm a tube Marshall guy all the way, but tube amps need to be pushed to sound good, and even a 5-watt tube amp is too loud for the bedroom. I like attenuators, too (a Weber MiniMASS in my case), but they can only do so much. Once you turn them down into the weeds, they compromise the tone.
When I need Marshall sound at low volumes, I use a Vox MV50 "Rock" model. It uses Vox's "NuTube" device to get tube sound, then couples it with a 50-watt Class D power amp. The head fits in the palm of your hand. Since the "tube amp" sound is generated in the preamp section, and the volume control simply varies the output of the passively-voiced power amp, it retains its cranked-stack character down to near-zero volume levels.
It also makes a great backup for gigging. Into one or more 12" speakers, the MV50 sounds awesome, makes a serious amount of noise, and takes up no additional space in the car.
For quiet recording at home, I would recommend going direct, using a speaker-modeling direct box (I have an H&K Red Box), or a load dump with software IRs in your computer. My reasoning is, you're likely to get background noise bleeding into your guitar track if you're micing a quiet cab. A direct box takes all the background noise (not to mention a less-than-perfect room) out of the equation.