What should I upgrade first amp or preamp?


I need your help. I have OPPO BDP-105 connected to PASS Labs XP-10 and XA-30.5 driving 89 dB at 4 Ohm Snell C7. Looking to upgrade my system and planning to spend $ 3000-4000. I live in the apartment building and unfortunately can't listen to music very loud (no more than 58-62 on the XP-10 display).
What would you suggest to do, upgrade preamp to XP-20 first or amp to two XA-60.5 or to XA-100.5 and why. Upgrading an amp is more problematic due to the space constrains.
What will I gain and what should be the difference in sound in each of those cases?
Thank you.
karapuz
That all sounds good to me, assuming that the Analysis Plus interconnects are the XLR versions. Frankly, I don't see anything that particularly stands out as a weak link, although I have little familiarity with the XP-10 preamp.

Regards,
-- Al
I know you aren't a big fan of tubes but if you were to throw a Herron VTSP-3a in there, the sound wouldn't go tube-ey. You'd just get a better sense of space and timbre without sacrificing any dynamics. I've been a high end passive guy forever and even tried some SS preamps but it wasn't until I tried a very good tube preamp that I finally got the sound I was looking for.
Of course, they are XLR's. What's the point to have fully balanced equipment without using XLR interconnects.
Karapuz,
What are you trying to improve? It is not stated in your original post.Brownsfan suggested the Modwright modification to your Oppo and this is an excellent upgrade in sound(and a very good value).You say you don`t want tubes, okay,what are you seeking in you system that`s currently lacking? Almarg was right in not assuming you naturally have XLR cables,how would he know?
Regards,