Something that approaches the detail of the Senn HD800, but smoother and/or less bright. The LCD2 and Alpha Dog I had were nowhere near satisfactory in those respects. The much cheaper Mad Dog at least had the treble balance right, although the detail was somewhat lacking. Apparently the planar design is good for bass, but you can see in innerfidelity's reviews that treble is typically a problem, and I suspect that a single-driver planar is limited there.
I had hoped to get to listen to an HD8000
S last month at Capital Audiofest last month, but if there was a set there, I missed it. Supposedly the peakiness in the treble of the 800 got engineered out.
Planars (at least in theory)
should perform beautifully at high frequencies due to their extremely low mass. I had no complaints about the treble of the Audeze EL-8's I heard at CAF, at a much lower cost than any of the LCD models.