Atenuator Atenuats how many DBs?

[Alpha579]

Hey all,
I was messing around with an attenuator for my 15watt valve amp (i know its small, but its non master volume and gets a wee bit loud for my bedroom), and was wandering; how many dbs of attenuation do u need for it to be effective? Bearing in mind im using a 15 watter,
Thanx for any input,

[Alpha579]

Sorry all, found out on the Ampeg website, sorry for inconinience....