depending on how often you use it, it may be worth switching it completely off when its not going to be used for a while.. it'll save 70w on all time.. the adage of amps requiring to be kept warm all time is imo a little wrong. 20 mins before listening, for me is all they really need.

and perhaps as Barry does, swap out the amp in summer for one that doesnt heat the house for you. if your amp is in a spare room, you could turn down the radiator in that room so you get benefit of the heat when its on.