Gavo,

I really want to make sure I understand you so I'm going to use a quick example.  Say you have a hardware store website.  You have interior pages for plumbing, lawn care, etc.  You want each of those pages for the different departments to rank as best they can, correct?  I feel like the answered marked "Good" is actually not the best answer for what you are asking.

Well the best way to do that is not _jus_t by linking to your homepage.  So long as they are healthy links, having a website that blogs about your lawn care equipment and the amazing prices with a link to that page is going to help that page rank higher for that term.  If you just have them link to your frontpage which is directed toward the business name and "hardware" you are going to the long way to the top of google.

Yes, having tons of really good strong links to your front page will give your site more Domain Authority and trust and will help your interior pages, but not nearly as quickly as if you actually have multiple links to each of the pages.  Just taking a pages Page Authority from 1-2 to 25 with a really strong Domain Authority can get you to the front page so long as the page is optimized and has a good amount of trust and links.

You're speaking of the difference between Page Authority and Domain Authority.  In my experience in regards to SEO, you should treat each page as though its a separate website, that needs good solid keyword targeting, rich content, links on social media, and links from other creditable sources.  Building a ton of links to your front page will give you slightly better Domain Authority but this doesn't help your interior pages rank as quickly (unless you have a Yelp like site with extremely high +90 DA).  If each of your interior pages is treated as important as your home page, you will see better PA and DA for each of those pages and almost certainly end up with higher SERP results.

On a side note, beware of directories.  Unless you are specifically campaigning for Local results, directories could be spammy, non-creditable links that actually hurt your sites authority.

Hope this helps.

I find Domain Authority to typically be a much stronger candidate for results.  Installing the "mozbar" to your browser and using it (make sure you are logged into Moz) will really help show you what I am speaking of.  Many times, websites like Yelp will list on the first page for a business with a page that has a Page Authority of 1, but the DA of the site is so strong that it outranks other pages with a much higher PA.

The way I see it, PA will help get a certain page to rank, but DA will get all your pages to rank (which will help diversify your SEO thus bringing way more traffic to your site for different sets of keywords.)  Remember, each page should be for a different topic, so if your front page is for your main target keyword strand, and you have a high PA but a low DA, your site is likely to rank for that one term, but all the interior pages wont.  Whereas, if you have a higher DA, you can rank higher for every page on your site with different keywords.  The best way to do this is to link multiple pages from your site.  For instance if you are guest blogging, don't just include a link to your front page.  Try to include a few links to interior pages as well for relative topics.  Also, I have actually seen Google Adwords give stronger DA.  I know many will argue this, but when campaigning on adwords, you can send different keywords to different pages.  Users entering your site through interior pages is a good thing, as Google seeing everyone come to your site from the front page can sometimes lower your DA.

Hope this helped!