what connections and cheap cables are you using?
how. old might they be as cheap cables can be blurry,did you try a better one + clean dirty tv screen
Can you try the box on a different tv?
i found with my H2S that sd was blurry but in av settings there is an option to view sd as 1080 - sorted it out no problem
Whats your a/v settings, on the zgemma remote press menu, setup, system, A/V settings....I find best results for SD are
Automatic resolution - disabled
Mode - 1080i
refresh rate - 50hz
display 4:3 content - just scale
display 16:9 content - just scale
Green button to save, try that and see, it could also your TV needs calibrated
How old is your tv? , expensive or cheap model not being cheeky , as newer expensive tv panels make a lot of difference .