What are good amp valves for heavy metal tones I have a Vox valvtronix 30w and want to juice more gain out of it?

To enhance heavy metal tones in your Vox Valvetronix 30W, consider upgrading to higher-gain preamp tubes like the ECC83/12AX7 or the ECC81/12AT7, which can provide more saturation and aggression. Brands like Tung-Sol or JJ Electronics are popular choices for their robust sound and reliability. Additionally, you might experiment with power amp tubes, if applicable, to further shape your tone and gain response. Overall, pairing these tubes with an appropriate EQ setting can help you achieve the heavy metal sound you're looking for.