I dare anyone to listen to James Newton Howard and Friends album with a properly amped HD800.
Although not as good as CD quality, you can listen to the full album here.
Yes, it's the same James Newton Howard who is known for his film scores, but this is one of his earlier experimental albums. I wouldn't say that this is one of his seminal works as a music composer, but as a live album, this is a truly reference-grade recording that will please even the most demanding audiophiles. It's not slow-paced, laid-back music at all, but the HD800 sounds excellent with it, retrieving every last bit of detail.
Sheffield Labs was THE audiophile label back in the 80's. MFSL and GRP were two other well known audiophile labels of that era. I used to own this album on vinyl - it was a great test/demo album.