Unfortunately I no longer have the PP8 to compare directly. Edit: I can say I very slightly preferred the PP8 over Andromeda. I believe I've got a comparison of those two in this thread (if not it's in another thread on this site). From memory I'd say the Solaris would also improve on most of the same things against the PP8- separation, layering, sense of space front to back. The PP8 was pretty resolving, so the spread might be a little less but Solaris is still a step ahead. Where the two are going to differ most is in-between 4-7k and this is where I'd really need to directly compare to give you some worthwhile feedback.