Subdomain vs subfolder?

I have an adult tube site and i would like to add a separate blog part where i could target other adult keywords like sex toys reviews etc.. I tried just writing an article and posting it on the tube site but it looks awful so that is a no go. My site has DA 15 and if possible, i would like to transfer that to the blog section rather than start with a fresh domain. Ideally being able to put a different theme on this section would be great. Reading up on it today and either creating a subfolder or subdomain seems to be the way to go. I just basically want it to look like a different site but keep the domain authority iv built up to give me a head start. What would yous recommend?.

Google considers subdomains as completely different sites from the main domain thus no DA will be inherited.