Goldring DR150s.
I have heard neither of them personally but I have heard good things about both.
The best I have heard about the 668b is that they beat MS1. The worst I've heard is that they are a bit weak in the mids when compared to the cheaper superlux.
The best I heard about the Goldrings is that they come really close to Senn HD600/580s.
BUT what I heard about both of these phones is that they are well worth their money. Fun fact, the 150 in Goldring DR-150 stands for the price they used to retail for (in pounds). They now sell @ 60 pounds.
If you pay 83$ for the 668b, you're being ripped off. They might sound 83$ good but I just ordered them for 30€ shipped which is 43aus.
At thomann.de, you can get them for 43$+36$ shipping to Australia which isn't a lot cheaper but certainly safer than ebay. The problem is that shipping to Australia is expensive if the product is in Europe.
I'd say you'd be on the safer side by ordering DR-150s because they are more widely known and have been reviewed more times than the Superlux.
I just bought the Superlux because the Goldrings would be twice as much for me, but for you the 150s would be the better deal.
Keep us up to date and post yr impressions!
PS: If you are patient I could order the Superlux ones for you and ship them to you for 20aus$ shipping instead of 36. But that would be without insurance etc. I don't know whether things get lost when they check the package at the customs in Australia, but I could mark it as a gift.
PS2: apparently this thread is being continued here http://www.head-fi.org/forums/f4/sho...d-668b-483794/