I'm currently listening to an Egon Wellesz symphony(from a CPO cd, very nicely recorded, Naxos should require their engineers to learn from the CPO production team, it could help them with their tendency to produce very mediocre sounding orchestral recordings!) through my HM-602/ HE-4s/Zen Head portable amp. As I mentioned it is a nice recording w/ lots of nice apparent hall ambience & sounstage information. If I had to pick an area to criticize it would be the mid frenquency sound are a bit recessed. I've read that this is a common trait of the HE-4s when new & basically unbroken in (I have less than 20hrs of play time on them including 2 or 3 full Purist Audio Designs burn in CD cycles) . Bass is tight & punchy & fairly well extended. The treble is pleasing with nice detail & sparkle. All in all you can tell you are listening to full range uncompressed recordings & not the MP3 versions of such. I've gone inside my Zen Head amp & tried different setting w/ the internal switches, The current setting that seem to work best for the time being are these. The input switch is set to 10k, crossfeed switch is on (crossfeed done correctly,& I believe very tastefully in this amp, sounds much more realistic to me) & the gain switch is set to high. There is absolutely room for improvement (more midrange prominence/extension), but I'm pretty pleased w/ the sound I'm getting. I won't even give this set-up a backhanded compliment by saying "very decent for a portable set-up", because I know there are many people listening to home mid fi systems that are'nt as good sounding as this (but I also realize that my "portable rig" may be more expensive than what their home rig expense was(What was I getting to ?, who knows,I'm a crazed audiophile) .