And how much will one need to spend for an amp for the LCD-2, though?
I probably should have phrased this differently - there are amps that have great synergy with the 650 but the 650 is where the Headfi Nervosa meme came from where you buy a $300 headphone and a $2,000 amplifier to soup it up when you could have just bought a TOTL headphone to begin with and a cheaper amp. There are lots of amps that do well with the 650 including solid states and DAPS but in terms of pushing the most out of it like removing the veil (I don't believe it has one and people are looking for something that it's not when they say this btw), increasing detail, less muddy bass extension and bloominess, etc. you need something that just has more control of their drivers and that usually only comes with very expensive tube amps or DIY ones like a Mainline or Crackatowa. If you want the classics then a Bottlehead Crack/Valhalla 2 work wonderfully with the HD650 but to transform them into better technical performers you need to spend more on amplification. There's just no way of getting around that. Personally, I'd rather spend them on more technically capable headphones which I do believe the Atticus and LCD-3 are. Their mids are the most liquid, smooth sounding with a much better treble extension, soundstage, microdetail retrieval ability than the 650s.