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

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  

So now I know what to do with my four grand...keep it and use it for more tubes.

Uh oh, Umm Wolf? You mean these things are supposed to glow?
 I thought.....

Absolutely in the team photo.

One of their greatest strengths is that while they may not be the "perfect" pairing with a given set of speakers, they typically sound damn good with everything.  So, as far as an investment that is nice to know.

I've run my 250.8 with power hogs, and with easy loads.  I've swapped out amps on the same speakers.  Typically, the pass still sounds the best.  

The 250.8 however I believe is one of Nelsons best designs.  I like it better than the 350.8 when I've heard it. 

Just has a really great midrange.

There are a number of great amplifiers out there, both tube and solid state, for a range of prices.  I have been lucky enough to have many of them from ARC and CJ tubes to a number of Rowland, Levinson, Krell and, yes, Pass Labs amps including most recently the XA100.5's.  I have not owned the 0.8 series Pass amps yet.  Having said that, a critical factor for most amps remains the speaker-amp interaction.  I have ML CLX's and Pass Labs has recommended the larger X 0.8 amps which they feel are better suited to driving the CLX's than the XA series due to its need for higher voltage and amperage as well as its punishing impedance curve.  Your taste in music and in what aspects of music reproduction  are most important to you are obviously critical as well; no amp or speaker is perfect.  This sounds trite, but I really think that you need to hear your speakers with the amps under consideration.  Others have opinions, but you may not share them.