Pass labs upgrade path

Oy.

It depends how much power you need, how big is the room 

what most people don’t know Thst inside there are many upgrade paths as in parts quality Thst can be bettered  for example  Vishay naked resistors in smaller1/2 watt type , worlds best Belleson regulator's these dramatically lower the noise floor .

ever capacitors ,especially output caps  . For they donot use the absolute best ,that-is reserved for their top efforts. Myself even upgraded the transformer even the internal wiring . It depends how far you-want to go .this is the most cost effective . I have modded everything in. My system and have been doing my own loudspeaker upgrades on the Xovers for years , being an ex dealer , my technicians showed me , and did you know as a rule only 25% of the cost goes into the product on average ,the restR&D overhead and markup including packaging , that’s why modding brings such high sonic  returns for the monies ,that’s how Modwright became so successful.

I think an XP22 is the best upgrade option. You will need to go to an XP32 to better it.

Depending on how much power you need, it's worth listening to the XA power amps before you upgrade your existing power amp. 

I was very happy with upgrade from XP20 to XP22, and X250.5 to X250.8...did not upgrade both at same time, but rest of system was same during both upgrades...have not heard the X350 series or the XP30...there also seem to be many who find the X250.8 different than the X350.8 but equally good...the high power XA amps are in my opinion way better...

Passive preamps take more than they give back. The Townshend is not passive, it uses a 12VDC wall wart, so what you are buying is an $8,000 volume control. And Pass XA25 is far from the best amp. Keep looking, and have fun.