I just bought my 555's from amazon for $100 with free shipping. . .I would not recommend buying any Sennheiser product from eBay, as they are very adamant that they WILL NOT accept any headphones purchased from any eBay place for warranty period. They will only accept them to repair them at your cost. . .or so I have read many places. I don't know if the prices work for you in Canada also, but check out Amazon. . .I bought mine directly from them, not a merchant. Personally I'd get the HT Omega sound card as opposed to a amp and dac, but then again I have not messed with them. HT Omega's eq can tweak your audio quite a bit (in a good way). . .just sit down, and take a little time to adjust it to preferences. On my Striker, I usually start with the "Soft Rock" as it gives the best starting point to my taste (rock, heavy metal, industrial) and produces a nice rounded overall sound. Then again this all just MY opinion. . .although everything here is just that opinions, lol. (Unless there is scientific evidence, nothing is a fact
Also, you don't HAVE to get the Claro with the built in amp. . .my Striker works just fine. An amp will only improve the sound quality, especially the 555's. I am only running mine through my surround sound receiver, as I already stated. . .I'd say straight from the sound card is like 85-90% of what it is from the receiver. . .so its not a MASSIVE difference.