Well you asked so here is my opinion. I owned for quite a while the Pass X350.5 amp and the XP-10 preamp.
The XP-10 preamp to me was average. The step up from it was the XP-20 which has 2 separate chassis, I never heard this unit but I didn't like having to use extra rack space for the units.
I compared directly the Pass X-350.5 to the newer XP-350.8. I just did not like the newer X350.8. To me it sounded much more closed in and had less treble presentation than the older 350.5. Caution either chassis gets very hot!
Eventually, I tried an Atmosphere M-60 3.3 and sold the Pass. Today, I own the Bob Carver Raven 350 tube amps.
Each step improved my audio enjoyment as I moved away from Pass.
ozzy
The XP-10 preamp to me was average. The step up from it was the XP-20 which has 2 separate chassis, I never heard this unit but I didn't like having to use extra rack space for the units.
I compared directly the Pass X-350.5 to the newer XP-350.8. I just did not like the newer X350.8. To me it sounded much more closed in and had less treble presentation than the older 350.5. Caution either chassis gets very hot!
Eventually, I tried an Atmosphere M-60 3.3 and sold the Pass. Today, I own the Bob Carver Raven 350 tube amps.
Each step improved my audio enjoyment as I moved away from Pass.
ozzy