hey guys

I have a Peavey Valveking 212 combo. I want to retube the thing to get a better tone. the tone I'm looking for would be something that lives in the range of hard rock to heavy metal. somewhere in the realms of Pantera and System of a Down where I can help give me a better 'chugging' sound and a more defined bottom end.

I've never retubed an amp, or taken one to get it done. so should I look into getting preamp tubes as well as power tubes?