Based on Stereophile measurements of the XA25, I would say that the amp is good for up to 30 watts per channel clean. Anything above that will start to have distortion/clipping problems (not that you would really notice any difference between 25 and 30 watts, lol).
That being said, it takes a very beefy power supply and large heatsinks to run a stereo amp at 25 watts per channel "full Class A". That amp is going to have extremely clean and full sound. This Pass XA25 has a nice mellow full sound. Very nice to listen to, but it is somewhat laid back when compared to more dynamic amps.
The BHK 250 will likely be able to give you slightly stronger deep bass strength, with it being a 250 watt per channel Class AB amp with good size power supplies. The BHK is a cleaner and more neutral sounding amp than the Pass XA25, but it is still mild sounding (most likely due to the stock Genelex Gold Lion tubes). It's likely that you can get this amp to sound more exciting with PSVANE or Electro-Harmonix input tubes.
I'm not sure that you would really notice or care about the slight increase in deep bass strength, since it's a 6" bookshelf speaker, but I could be wrong. Going from XA25 to BHK 250 is really about a sonic signature change.
That being said, it takes a very beefy power supply and large heatsinks to run a stereo amp at 25 watts per channel "full Class A". That amp is going to have extremely clean and full sound. This Pass XA25 has a nice mellow full sound. Very nice to listen to, but it is somewhat laid back when compared to more dynamic amps.
The BHK 250 will likely be able to give you slightly stronger deep bass strength, with it being a 250 watt per channel Class AB amp with good size power supplies. The BHK is a cleaner and more neutral sounding amp than the Pass XA25, but it is still mild sounding (most likely due to the stock Genelex Gold Lion tubes). It's likely that you can get this amp to sound more exciting with PSVANE or Electro-Harmonix input tubes.
I'm not sure that you would really notice or care about the slight increase in deep bass strength, since it's a 6" bookshelf speaker, but I could be wrong. Going from XA25 to BHK 250 is really about a sonic signature change.