There's a healthy difference of opinion re how to get started in moving up the head-fi chain. One school of thought is to settle for a rig that's a bit less than ideal for the sake of your wallet. This could be called the holistic approach, i.e., balance all the parts for the best possible sound within your budget.The other school of thought is to go for the gold in one or more key components, even if it means way less bucks for other components. This could be called the elemental approach.
Both have their merits. The holistic gives you good SQ for the buck. And you can always sell the parts as you move up the chain and replace them.
The elemental also gives you good SQ if you choose wisely. For example, if you go with the HD650 as your personal quality standard and spend far more than you can afford to get it, then you'd have to scrimp on the source and amp. At the most basic (as one of the other posters commented), you could use computer as source and use the line out to the LD2++. And as others have said, the SQ in this setup is very good.
I prefer the elemental approach because it keeps the key part of the rig constant -- the headphones. The 650 is an excellent reference, and it's arguably the industry standard. From this vantage point, you can judge the changing mix of components in your evolving system. You'll hear exactly how a different component will impact your system.
If you can't afford an after-market cable for the 650, go with the stock until you can afford it. After the amp, the next purchase could be a reasonably priced DAC, which would allow you to bypass the computer's sound system (card or built-in) via the USB. (Make sure the DAC allows for USB input.)
Among elementals, there's a difference of opinion re priority. Should you buy the best cans or the best amp that you can afford? I'd say cans, first, but there are good arguments for amps first, too.
