Which amp would you choose and why - Pass Labs XA-25 or First Watt F8?

Forget about power for a moment. XA25 is a normal pass amp. If you like pass sound (smoothened out, clean, safe & a bit boring), get XA. If you are looking for something raw and true to source, get Firstwatt. It should satisfy your speaker's hunger though. Look for a J2 as well

I own both. The XA-25 will play a bit louder and more dynamic than the F-8. I listen to the F-8 religiously acct. it sounds more musical, sweeter & more accurate than the XA-25. Plus it is a more intimate sound. All my listening is thru LS 3/5A speakers. I own many low watt tube amps and I still listen to the F-8 above all of the these.

@ghdprentice i use the balanced out on my preamp because it goes through another set of tubes.  i  tested it with my previous amp and using balanced out sounded more spacious and 3 dimensional than using single ended out.  

@avanti1960

Imteresting. Nice looking system and room.

I own both. The XA-25 will play a bit louder and more dynamic than the F-8. I listen to the F-8 religiously acct. it sounds more musical, sweeter & more accurate than the XA-25. Plus it is a more intimate sound. All my listening is thru LS 3/5A speakers. I own many low watt tube amps and I still listen to the F-8 above all of the these.

@powder99

Problem is the OP has Tannoy speakers that dip down to 2 ohms. Your LS3/5A’s are 15 ohm speakers. This is a huge difference. I’m sure I’d prefer the sound of the F8 into your speakers over either amp into the Tannoys.