As for how the XA160.8 sounds compared to the XA160.5, here is what I think after comparing the two today:
- There is more bass with the .8. It is deeper, punchier and thicker.
- The scale of the .8 is much bigger than the .5, especially at lower volumes. At about 90db the scale starts to get similar.
- It may be that the .8's don't have any less energy in the upper frequencies than the .5's and my impression is because of the extra warmth/bloom of the .8's (giving the impression of less treble). Today I noticed that by boosting the tweeter resistors on the Alexias by .5db it sounded more similar to the .5's.
- In my room, with my gear, the .5's sound more open on top and the presentation is leaner. This allows me to hear the texture of bass instruments more clearly. That said, switching from the .8's to the .5's the upper midrange of the .5's sound thinner and depending on the content I may miss the .8's.
- The .8's may have better 'deep' bass control than the .5's, but since I switched from MIT power cords to the Shunyatas I have no complaints in that area with either amp.
For rock music, I LOVE the .8's. The rich, meaty midrange presence and bloom makes it sound like a tube amp and is great for feeling like you're in a club. It makes me feel like I have much larger speakers and not want for Maxx's or XLF's.
For jazz, I prefer the .5's. I haven't listened to enough classical yet.
Both are great amps and I have a tough decision to make on Monday!