timmmay:

geekiegeek: What are peoples thoughts on what an immaculate pair of HD650s is worth second hand?

$50 at most, give me your bank details and I'll send it right now ;)

joker97: $300-399 wide range because

geekiegeek: Have just ordered myself the Sennheiser HD700s from the states. Found a good deal on Amazon for a open box return pair, NZ$696 which is half what they go for here.

Currently own the HD650s so will be interesting to see what the improvement is, expecting a slightly wider sound stage and more clarity in the highs and mids with maybe a little less bass. 

What are peoples thoughts on what an immaculate pair of HD650s is worth second hand?

NZtechfreak:

geekiegeek: Have just ordered myself the Sennheiser HD700s from the states. Found a good deal on Amazon for a open box return pair, NZ$696 which is half what they go for here.

Currently own the HD650s so will be interesting to see what the improvement is, expecting a slightly wider sound stage and more clarity in the highs and mids with maybe a little less bass. 

What are peoples thoughts on what an immaculate pair of HD650s is worth second hand?

About $400-450 or so.

I'd recommend holding on to them until you've had a good chance to hear the HD700. You may find that the HD700 sound signature is not to your liking and that you actually prefer the HD650, despite the HD700 possibly being the more technically proficient headphone. From what I've seen the HD700 can be somewhat polarising...

timmmay: I have a PPA headphone amp sitting on my desk, all sorts of good stuff inside, fed with an optical input and a DAC inside it. Unless you have headphones that are hard to drive IMHO it makes no difference at all - helps a little with the headphones I have, LCD2. I wouldn't waste your money unless you have magic ears or too much money. If you're in Wellington you're welcome to come try it out.

networkn:

timmmay: I have a PPA headphone amp sitting on my desk, all sorts of good stuff inside, fed with an optical input and a DAC inside it. Unless you have headphones that are hard to drive IMHO it makes no difference at all - helps a little with the headphones I have, LCD2. I wouldn't waste your money unless you have magic ears or too much money. If you're in Wellington you're welcome to come try it out.

I think some headphones benefit from it more than others. I'd say the lower end don't usually, but in a double blind test I can tell the difference easily on my HD650's and T1's. 

I would say to the OP to upgrade his cans before spending on a headphone amp. Much better return on your investment.