I know the XX-2 pretty well and I would say the Delos is an improvement over the XX-2 in every way. Lyra willl give you a bit brighter top end compared to the XX-2 which may or may not be desired.
On the other hand if you like the Koetsu sound, I would recommend an Allaerts or Miyabi instead of the Lyra.
On the other hand if you like the Koetsu sound, I would recommend an Allaerts or Miyabi instead of the Lyra.