Are Pass Labs amps probably the best ever you can buy ?

Pass are superb, there is better.
for less, shop around, listen and learn. 
I went with McCormack. —-and no turning back now. 
Im hooked on Steve’s house sound. 
 Passed up a Pass mono pair for the McCormack monos’, could not be happier, your ears will tell you what you like, when the goosebumps hit......you will know. 
Enjoy the hunt. 

I’ve always liked Nelson Pass and his designs but unfortunately I’m tied to a little Dennis Had single ended tube amp driving efficient speakers...I can’t break loose...that new 25 watt Pass amp seems SO cool...but I fool myself into thinking tubes are just better sounding...maybe the SIT First Watt amp...no...I can’t do it...damn.

@wolf_garcia 

Take a look at the SIT3. It uses 2 complementary input JFETs to drive an autoformer for voltage gain followed by a single power JFET output actively biased by a MOSFET constant current source. A real damping factor, 200kR input impedance, and a near double of it's output into 4 ohms...it's a real amp with real triodic response curves that makes real power. 

Didn’t I just mention the SIT amp? Are you trying to make me feel sad? I've read a lot of reviews of that thing but I’m stuck!..I REALLY like my Had amp...it just sounds so good...and the tubes glow...plays plenty LOUD if need be simply since my speakers are (supposedly) 99db...Why? Why? I’ll just have to think of something else to do with four thousand dollars...*sigh*...

Regarding the SIT3, an important point to note is that it has an extremely low gain (for a power amp) of only 11.5 db.  Power amp gains are typically in the mid to high 20s.  Most Pass Labs amps have gains of 26 db for example, although most of the other First Watt amps have gains in the teens. 

Consequently it can be calculated that the SIT3 will require a single-ended input (it does not provide a balanced input) of about 3.2 volts to be driven to its maximum power capability of 18 watts into 8 ohms.  If a digital source having a volume control is used without an active preamp it will almost certainly not be able to provide that much voltage, even with the volume control at max.  And in many and perhaps most cases vinyl or other analog sources won't be able to do so even when used in conjunction with an active preamp.

I considered purchasing a SIT3 recently, but that factor made it a non-starter for my system.  I went with a Pass Labs XA25 instead, which I have been delighted with.

Best regards,
-- Al