Hmm...I understand scholars tend to classify only 9 main Chinese
*dialects, but within these 9 main dialects are subsets. No, I'm
not a linguist, but I've studied linguistics and still keep my
interest in this area.
The northern Chinese would sound pretty similar to Mandarin
(depending on how close the dialects are to each other). Even
Beijing has its own dialect, similar to Mandarin. What we call
Hockchew is actually Northern Min.
Dialects even cross provincial boundaries. Southern Min is spoken
by people in both Fujian (Hokkien) and Guangdong (Canton)
provinces.
Anything else you want to know? My 2+ years in Shanghai has been
very fruitful 
*Linguists would call them "languages", as true dialects should be
mutually intelligible, which the Chinese ones are not. Examples of
dialects include Teochew-Hokkien, which comes under South Min
dialects. Another example would be Southern American-Black
Vernacular American, which again are mutually intelligible, even
though there are substantial differences. Even Chaozhou Min and
Shantou (Swatow) Min are actually dialects of each other, with some
differences. Even Shanghai itself has 3 dialect subsets - Chongming
Shanghainese, city Shanghainese and rural Shanghainese (those
spoken by Qingpu, for example).
