The ER4S are my favourites for symphonic music, even when I'm home. They sound quite good actually out of my WA3, though I'm sure a ss, low impedance output amp is probably a best choice.
Mahler, Tchaikovsky, Brahms, they all sound pretty good despite the lack of a wide soundstage. Tonally I think they are superior to any cans I tried.
With chamber, well, I prefer the K702, because of their pinpoint accuracy or the Beyers for their warmth.
Having said that right now I'm listening to Bach's keyboard concertos (Christoph Rousset on Harpsicord, Decca) through a E7 + ER4S and it's pure bliss!