Pass labs xa25 amp and BW 804 d3?

A minor point but one that should probably be mentioned is that the Vandersteen 5 has a built-in amplifier handling the deep bass. And it is designed to be used with a passive high pass filter inserted between the preamp and the power amp, which rolls off low frequencies by 3 db at 100 Hz and at 6 db/octave below that frequency. (The built-in sub amp provides a complementary frequency response which restores overall flatness). So the power that is demanded of Macguy’s X250 is significantly reduced relative to what be required if it were driving a comparably efficient speaker full range.

In any event, it appears that the Vandersteen 5, like the currently produced 5a Carbon, is rated at 87 db/2.83 volts/1 meter, but apparently has an 8 ohm nominal impedance rather than the 5a Carbon’s 6 ohms. Assuming those specs are accurate it can be calculated that at a typical listening distance of say 10 feet, and in a medium sized room, two such speakers will produce an SPL for a centered listener that is in the vicinity of 95 db when both are driven with 20 watts. Enough for many listeners on most or all of their recordings, but certainly not enough for some listeners, especially on recordings having wide dynamic range.

I do not agree with the popular audiophile axioms, "the more power the better" or "enough power is never enough".

I disagree with those axioms as well, Charles. A point that seems to often be overlooked by proponents of those axioms is that for a given level of amplifier quality more watts usually = more $, at least within a given amplifier topology and a given class of operation (A, AB, D, etc.). So if a given amount of money is to be invested in an amplifier of a given topology and class of operation, choosing an amp that has more power capability than necessary may very well mean that more of those dollars than necessary will be directed toward watts rather than toward quality. At least that’s how I see it.

Best regards,
-- Al

Well this explains Macguy's observation of his Pass Labs X250 not leaving class A operation while driving the Vandersteens, 95 db SPL is plenty loud for many listeners. Al thanks for the additional information and the always keen commentary. 
Charles 

I own a Pass XA-25. When I bought it I owned a new CJ ART150 stereo tube amp and a CJ Premiere 12 monoblock set up. I’ve had the legendary CJ Premier 350 solid state amp. I drive Wilson Audio SOPHIA II’s. I got here with an XA25 after exchanging email with Nelson Pass when I was thinking of a First Watt to try out. He re-directed me to take a look at the XA25. That was in November 2018. I have sold the ART 150 and other amps. Compact and commanding. I read the STEREOPHILE review and the technical assessment. All I can tell you is the little amp commands the Wilsons with authority. My sound has never been better. It paired extremely well with CJ single ended pre amps such as the ET-5 and Premier 16LS2. I tried a Pass Labs XP-10 which was a very good pre, but traded it for the XP-20. This little amp can and does command with authority. The reviews of the sound are dead on. I also use a ELAN Z cooling fan as well; it of course runs hot so the fan helps.

I received my Pass Labs XA25 today. It easily drives my 804s and it is actually runs just as cool if not cooler than my emotiva xpa 2 at high volume. It barely gets warm to my amazement. Sound quality is spectacular even though it is yet to be broken in. I think I will invest in the Pass Labs Hpa 1 headphone/preamp combo as a preamp. I like to keep things simple. I don't need any bells or whistles for my 2 channel listening. Thanks again for the advice.