Interface crackle

Any advice here folks?

Audio link below:

[https://www.dropbox.com/s/7okxjv3kw486x9b/Interface%20Crackle%20copy.mp3?dl=0](https://www.dropbox.com/s/7okxjv3kw486x9b/Interface Crackle" copy.mp3?dl="0)

The above crackling appears every ten mins or even more often. Also there’s click and pops all over the shop.

I’ve followed various online guides… matched sample rates in daw and interface / increased buffer / lowered bit depth / tried different daw.

Had exact same problem with last interface but less severe, I thought it was broken… which makes me think that it’s my computer. Maybe I should try it on another mac?

The firewire is connected via one of these adapters as I don’t have same firewire connector on my macbook:
http://www.amazon.co.uk/dp/B003WVOX20/ref=pe_385721_37038051_TE_3p_dp_1

Any tech savvy folk with some ideas on how to remedy?

Cheers:)

Martin