It's hard to say without discussing more of the details.  A few potential plus/minuses that occur to me right off the bat- 

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More readers could mean more exposure to your measurements which could do more to both inform buyers and put pressure on manufacturers to stop repainting the same flawed designs and make better headphones. 

A website partner could mean funds for equipment and better access to more headphones to measure.  Or funds that give you more time?

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But would working with an established website that needs income (especially if they're paying you) mean that you would need sponsorship by the very companies whose products you're measuring and make it difficult to be honest?  Same problem our Govt. has...