Attenuators are all well and good if you want to get a decent sound out of a valve amp, but at lower volumes, however, you still have to have enough signal coming through to the speaker in order to make the speaker work efficiently, and not "fart out" (not enough signal getting through to get a decent sound).
Even with an attenuator, 9 times out of 10, a valve amp will unfortunately still be too loud to use at home and retain a decent sound (unless of course, you are after a totally clean sound, or just using it for very quiet practice).
I've been through a few with various guitar amps, the best one I had was a THD HotPlate paired to a 50w JCM800 2x12 combo. It was great for rehearsing, but just that bit too loud for use at home.
A small solid state amp is possibly the best way to go, or a headphone amp/amp modeller.