Am currently using a heavily modded QED MD45 (cheap basic amp modded to an inch of it's life) - it's not bad at all but I can hear it's shortcomings.
 
I am thinking of a 2nd hand Heed Canamp but am wondering what other amps I should be considering - budget is up to £200 2nd hand.
 
Remember, this is for the HD580's!
 
Any help much appreciated.

Anybody? 

 Well, I'd imagine if you asked 50 people this question, you'd probably get close to 50 different answers! But since I have only had one amp with my 580's, I can only offer that experience to you. I am currently using a DIY amp called a CKKIII (or CK2III, or more technically [size=x-small]The Cavalli-Kan Kumisa III ) as described here [size=x-small]http://www.amb.org/audio/ck2/ [/size] . Paired with a Nforce uDAC fed from my PC through the USB port, I really enjoy the sound I hear with my 580's. I feed it with lossless FLAC files through Fubar2000 and the quality is excellent.[/size]
[size=x-small] I picked up my CKKIII here in the For Sale forums for $150 but I generally see them run in the $150-225 USD range. Recently the uDAC's have been seen in the FS forums in the $60 range (I use the 1st gen uDAC and that is what I've seen being sold here) so that seems real close to your budget's range. The uDAC also has a built in amp as well as a DAC, but I wasn't ever satisfied using it as an amp. As a DAC it functions fine for us low budget folks.[/size]
[size=x-small] My rig is definetly on the lower end of the audiophile's scale make no mistake, but honestly, I have never been disappointed with my low budget setup.[/size]

I use a Shanling PH100 with mine. Works really well. I've tried a Grado RA-1 'clone' which was okay, and also have a Project Headbox which is a bit rubbish compared to the Shanling. I'm tempted to try a Little Dot 3, but I'm not sure it'll be 'better' than the PH100 which really does make the HD580s sing well.