1. No expansion that I know of. Widex is pretty vague about what the different modes do, but essentially (I believe) the PureSound is just that - a mode with minimal or no enhancements or processing (which IMHO is most desirable for music). They also talk about their "revolutionary" low latency in that mode, but I've never noticed any latency issues with this or my previous HA (Phoneak Audeo).
For me, PureSound is the cleanest for music, so that's what I'm using. The music mode just didn't sound right.
2. I like my music loud too, and I've not noticed so far any distortion or breakup in these HAs.
I'm also a classical listener, and the climaxes (Brahms, Beethoven, Tchaikovsky, Sibelius, etc) shake the floor, but sound clean.
I use an 80Watt RMS per channel amp, with very efficient speakers. So it can be plenty loud, lol.
I have a hard time getting into Shostakovich, some parts of his symphonies are impressive, but not easy to like the works over all.
Not familiar with Bruckner, but he's on my to do list.
Hope this helps, good luck...
