Cold weather means Tube Amp season! Don't forget to retube your amp!
Electro-Harmonix EL84 Matched Quad
Electro-Harmonix EL84 has a nice, warm tone in guitar amps, especially on cathode biased amps. Note that EL84EH tends to bias 'hot' and may not work well in fixed bias amps like Peavey Classic 30.
Price is for a matched quad.