More watts or better power ?

I think this article will be helpful.  Certainly relevant to your discussion title.  
https://www.primaluna-usa.com/less-power-more-bass

If you in fact need to do anything at all, consider power quality over more wattage.

Tablejockey's comment is on the money.  I just did the experiment outlined in the article with a 35 watt amp driving 86 db sensitivity speakers.  Only takes 4 watts to arrive at a 92 db level. As it turns out, for me, 92 db constant white noise at 1 meter is WAAAY louder than how I listen even given my listening position is 3-4 meters (not 1) from the speakers.  

Mark, you don't need more watts, unless you notice a lack of low-end at your typical listening level. That's a sweet amp that produces high current which is what you really want in your system.

The only addition I would recommend is power conditioning/surge protection. You'll get lots of recommendations here, so you should state your budget. Only sources should go into a conditioner, since most are current-limiting. That means a high-current amp like yours can lose dynamics due to the filtering used to lower RFI/EMI and noise from the mains. The result of power conditioning is a lower noise-floor which will reveal more detail, better imaging, and air around instruments.
Anyway, a Pass Labs amp does not need a PC, it is designed to reject common noise.

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.

You say you have a small house and the system is in a bedroom, so I'm going to assume a smallish bedroom.  You have a lot of equipment in a small room.  Can you provide a picture?  Why not tidy things up an get an integrated amp with built-in digital and phono?  To match your current setup it's going to be expensive, something like CH, Gryphon or ASR.  Think about it.

And because I have to run my speaker cables down into the basement and then up on the other side of the room (20' - 25') I have not invested in high end speaker cables.

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For the money your best single investment would be shorten the cable runs and use a lot better cable.  You can do what your doing just fine.

The difference in SQ between 1/2  meter and 8 meters is really not that noticeable with so so cable. BUT with any type of GOOD cable, it's a big difference.

1/2 meter of copper zip cord vs 8 meters of high quality woven 24 conductor, (silver over copper, OCC copper clad) cable. I KNOW there is a big difference in sound quality.

One step closer and a lot less money is 1 - 3 meter high quality speaker cable vs the 8 meters of cable you're using..

I always thought I can't stand seeing cabling running everywhere. After the eye opening experience 40 years ago, I change my mind. I used good cables and short runs because I had to at the time.. Working on the house.  From then on everything under 10 feet, unless it was a bass bandpass or a sub.. It's the difference in mid fi vs hi fi yet the same exact gear...

I chose to move the gear and planned that way from then on.. Crazy thing that is what led to a 10,000lb (24"x18"x18ft) slab at one end of a bedroom, that is just now being converted 39 years later to one of two sound room this one with built traps and 3 foot cable runs. That would have cost me 10k now. It was 250.00 back them. 2-3 yards of concrete and rebar.

HT cable length, who cares? It's a sound effect deal anyways.. 

Regards