With the current cold spell that’s just hit the country, you’d do well to get a monster class-A power amp like this Musical Fidelity A370-2. It sounds a lot better than an electric bar heater, but uses a similar amount of power. Rated at 50 Amps current delivery and 185 Watts per channel and weighing in at around 40Kg, this baby gets hots, very hot… Sound wise, its warm (no pun intended), smooth and controlled. It’ll have no problem driving the most demanding of speakers.
New price was £5500 back in the late 80’s / early ’90s, but still sought after today. Expect it to sell for £500-800 ish.