Dolphin creates a number of thumbnails for different jobs The current size for Icon thumbs is 32 px square and yes, if you alter the CSS to 44px the small thumbs will be enlarged and they'll look terrible.
You can change the size of any image Dolphin creates in /modules/boonex/photos/classes/BxPhotosConfig.php around line 18, but this will only affect new members and new posts. All earlier photos are stored at the original sizes. Thus, if you alter the icon thumb size to 44 pixels, the thumbs of existing members will look out of focus.
It's never a good idea to enlarge digital photos so you will need to download all your main photos which are currently 600 px and batch reduce them to 44 px if you wish to maintain high quality. A free program like Irfanview can do it and correctly rename the icons at the same time, but it's really a lot of work.
The question will be as always; is it worth it?