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

I havent listened to the F7, but have the XA-25 paired with a Cary preamps (SLP 98 and SLP 05) driving Spendor D9s (90db, 8 Ohm) and Chapman T7 (89db, 4 Ohm).

The Cary preamps and XA25 have amazing synergy in my system. The XA25 may only be spec'd as 25W but it sounds more in command of my speakers than the Rogue ST100 that I owned.

 I considered both these amps and even asked Reno Audio for a F8.  He told me to get a XA-25.  Said it was a better amp all around.  Took his advice and love it.  I have paired with an XP-10 pre and Salk Exotica monitors.  Wonderful, I have no desire to change it.

The XA25 is the much "safer" choice in that it has much more power and is stable down to 1/2 ohm.  From everything I've read (and I had the XA30.8 paired with similarly spec'd D7's), the XA25 will have better bass and silkier mids.  The F8 may sound a bit more agile but possibly lean in comparison. Your Tannoy's can go as low as 20hz and the impedance dips all the way down to 2.9ohms at 100hz.  I really think you will need the XA25 to drive those Tannoy's properly.  What amp are you using now?

I have the xa25, much more powerful than its rated 25w, especially at 4 ohm dips.  I have an F3 which sounds glorious, but not near as powerful. I’d love to hear people give their perspective on the F8.

These flea watt amps are a niche possession. 
   Get 250-300W min. !!!

 Headroom, the airy effortless sound will be awesome.    Even a 25W amp will clip very easily on average to med-high volume. 
 I learned my lesson years ago, I’m NOT saying Nelson or low watt stuff is bad, NO WAY!

  Having the reserve, and hearing the huge difference with power reserves will make a difference, if and when you want a little bit of volume.  
For a small room, and never wanting to push volume, it will be fine.
if you think you need to jam a few songs, those small W amps will clip!

  250W or more. 
I’ve been through 50, 75, 80, 100,125, 165W amps, once I bought my first 250W+ amp, never have I looked back. 
 Enjoy the music!