I'm at a meet right now.. Having just used a Meta42 and MG Head with two different sources and 580s, 600s, Grado SR0s, and Beyer DT831s, I think that it would probably be decent to open them up a bit and get the dynamcs going beter, particularly in the bass department, (not that it will turn the into a new phone) and it will give them some of the drive your portable might be lacking. We have one here, I'll give it a spin soon and get back to you later.