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

I'm very interested in Nelson designs and hope to upgrade to his low watt offerings for a smaller room I have. Does anyone have experience with the Pass Labs XA-25 and First Watt F8 amps? Both are rated at 25W. What main differences do they have? Which one has better bass?

Preamp: Cary Audio SLP98
Speakers: Tannoy XT8F (91db efficient)
Both are rated 25W into 8 ohms, but the XA25 is 50W into 4 Ohms and the F8 is 15W into 4 ohms...and many 8 ohm speakers still dip at times to 4 ohms or less...I think overall the XA25 is more powerful...many of the reviews of the F8 seem to include a comparison with the XA25...I loved the F7 with my Avalon Ascendant II speakers in a small room...
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!
i have an xa25 that is coming into its own after a week and there are moments of absolute brilliance.  power and drive with my 86db Harbeths is more than adequate.  Also running a Cary tube preamp.  
XA25 actually puts out 80 watts or so.  I have had one for a year.  The sound is all I could ask for.  The drop for the F8 at 4 ohms is not what you want.

I won't be trading unless I choose different speakers and that ain't happening.  I didn't get into this to spend my time lugging components in and out of my system.  
I'm current running a Musical Fidelity M6s PRX,so a pretty high watt amp. And it's great but maybe a bit too much power for a small living room.
I would not be too quick to accept that massive power is always better. I have owned massive amps (i.e., Pass x350) in the past. Headroom is nice, but the grace and Beauty of an XA isn’t there. If your objective is loud and slam, or powering planar, then you need that. But for really good bass and midrange an XA or tube amp is better for many people.
@ghdprentice +1

Completely agree and I have had several examples just in my own house. My Leben 15w CS-300xs sounds substantially better than a Cary SLI-80HS (80 watts ultralinear) with my Forte III’s. The Leben also far outperforms my 30w Sudgen A21SE with the same Forte III’s. My Pass XA30.8 (30w) paired significantly better than another Cary 120w amp with my Spendor D7’s. Circuit topology, transformers, impedance matches, etc all matter when it comes to amp/speaker synergy. It really is not as linear as just saying "get all the power you can" to ensure a good sound. That works sometimes, but not in every situation.

i wished it did too but i was able to use the balanced outs on my preamp and balanced cables by using a neutrik xlr to rca adaptor at the amp.  
sounds better than using rca to rca.  

Have you tried just using single ended preamp outs? I would be shocked if using the balanced out and converting to single ended would sound better than just using single ended. Pass is one of the greatest amp designers of all time. If he wanted to use balanced input they would be there.

i live 25mins from Pass Labs. Have been there a few times and given a tour and education at the same time. Great people, even meet the man.  i am a Pass Labs dude!  the 25 will have more bass control with your speakers.  the F8 is their version of a solid state tube amp. that said, the only way to really know is to listen to both of them
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.  
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.


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.
galacticmayan - I was in a similar situation owning Tannoy (Churchill’s) and intrigued to try a First Watt product. I emailed Nelson and he said:

On thing about our amplifiers, they all like the Tannoy products – not a surprise since that’s our reference standard. If you play them at reasonable levels, then the First Watt F8 would give you some of those qualities that people like in Triode amplifiers. If you tend toward neutral then the XA-25 would be an excellent fit. You can get more power easily, but I don’t think you would need it. best, np

I think 3 Easy comments are very astute. Like him I worried that the lower power at 3-4 ohms would prove to be problematic with the F8. BTW the Churchill are 94 DB efficient. Yours are 3DB less, so it’s effectively like half the power.

I’m fortunate, I have a 845, and a 211 tube based Set amps to compair with. Further, the buzz on Tannoy is they respond better when there is more power. So I opted for the XA25, glad I did, I don’t think the F8 would keep my happy (my room, sonic priorities, etc.)

Even playing large scale complex music at lower volumes, the XA plays admirably, even Nelson says the XA amp is neutral compare to the F8, to me the XA is warm enough. However at any higher volume, and given your speaker are down 3DB, I’m not convinced either is a match unless the room is real small, and, or, your volume is lower than mine.

Aside from the previously mentioned amps I’ve also got a pair of S60 Atma-Sphere amps. There is a lot of synergy with what a) 60 watts of power will do with the Tannoys, and b) using OTL tube amps. The palpability and transparency is to die for. As good as the XA is, the S60 drive the Tannoys better IMO.
For me, the XA is the right choice with the two your contemplating. All the best in your endeavours!

For those users of either amp. My DAC has a 6volt output, so I would plan to use a (quality) passive pre-amp. Is this OK?


I’m using a passive TVC preamp with my DAC to a FW SIT3 with Excellent results! 
I sold off my $10k active preamp and never looked back..