Low wattage doesn't always equal low volume. I have a 5 watt Class A amp that will pump out 110 dB of volume. If you're mostly playing punk and metal you're not going to be pushing for power tube saturation. You'll be getting most of your distortion from the preamp side. Don't worry about wattage and look at amps with a good master volume. Most amps these days have excellent MV's.
I can't recommend a Fryette Power Station enough. I'm picky and hard headed, and I want to hear my tube amps through a guitar cab. A PS allows this at low volume, or high volume.
And you can still line out into an interface. Solves so many issues.
When I was in a apartment ....... I used Amplitube on my computer and headphones ..... worked great !! The same ... of course not .... but it worked better than I thought