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Take soundstaging -- depth, width, localization, stability -- and the F5 is a champ. No drift, no wander, no blur. No etch or grippiness neither. The F4 appears even 'floatier' but those are very subtle matters appreciable only in a direct comparison. Which of course is what the man already said in his own words. Nelson is definitely equipped to not just design amplifiers but review them objectively. Take microdynamics -- those heart palpitations caused by a singer's or instrumentalist's unexpectedly emphatic inflections -- and I'd have to call the F5 superior to my most cherished valve amps. If that's directly related to circuit speed, the F5 certainly lives up to that obnoxiously ideal square wave graph we admired earlier. This returns us, again, to that ability for remaining involving at very subdued levels. There's enough wiggly, jumpy, kicking live factor left to be interesting and gratifying. It's all there, not lost in any THD fog.

At elevated levels, over the Zus and on vocal peaks, I did detect the occasional glimmer of spiciness, of likely response peaks in their widebanders which my usual valve amps don't bring out. On my Lowther DX-55-based Rethm Saadhanas, this happened as well but not objectionably so, just a presence-region tweak for some enhanced if ultimately not entirely honest fun but clearly intrinsic to the speakers, not amp. Nelson has done extensive measurements of such drivers and could tell you precisely what operational aspects of the F5 contribute. I'll merely confirm that yes, if your widebanders are spicier than you wish, the F3 would remind you less if at all.

The monster SuperPAC tweeters on my 98dB WLM Grand Viola monitors -- paralleled horn-loaded paper units high-passed at 800Hz -- told their own tales of F5 treble elucidation. This amp suffers neither high-frequency phase shifts nor premature coagulation. If infrasonics help recreate the full scale of audible recorded space per se, high frequencies light up the space around individual performers. The deliberately wide-dispersion WLM 'tweeters' (their low crossover point makes them rather more than traditional treble units) do this holographic lock to a much higher degree than the Zus. The power response of the upper end is higher too as is the perceived energy of the ambient field. In plain speak again, they soundstage like demons. The F5 builds out this asset with panache. Soundstage freaks with the right speakers to heighten this stereophonic illusion will be over the six moons and on the seventh. Way wide and deep far-out stuff.

It's no surprise that the F5 is no overdamped control freak. Unlike the S.A.C. il Piccolos from Germany with their 80dB of feedback and claimed full-bandwidth damping factor of 20,000 which described as "dry as dust and super slamming in the bass", the F5's so-called damping factor, though higher than all other F amps, is still modest in the scheme of things. It's innocent then of cyborg bass, my term for entirely unnatural low frequencies that sound hard as nails or concrete. Truthfully (I've waited to tell you this so you'd keep with this review), you could take my F4 report; add 15dB of voltage gain and 2-ohm happiness; season with just a touch more articulating action, separation and concomitant 'visibility'; add a smattering of treble energy and presto - brothers from the same mother.

Ditto for operational noise. All F amps are quiet like the proverbial graves. That's perfect for noise-critical applications with high-sensitivity speakers. Mum's the word as well on the 240V mains transformer inside the F5. With my wall power often about 10% above its rated value, some iron protesteth and goes into hum. Not this one. Even the piercingly blue eyes of earlier F models have gotten turned down by popular request so the power LEDs no longer sear your retinae. Super-clean bill of health all around for the F5.

Act Three. This is where the main actor bursts into song while being stabbed in the back. Opera and all. We call it the conclusion. So, Nelson also is right about the 1-hour improvement. I didn't clock it but after between one to two spun CDs, the amp arrives and settles down. Could I tell the F5 runs on inferior feedback-fossil fuel compared to the other Fs? No. I have tested tube amps with selectable feedback where even small amounts of 2dB were clearly audible. Usually but not always, those did sound best with zero feedback on the speakers I used. Feedback then did dry out things, curtailed elasticity and swing if you will. However, I hear none of those drawbacks here.
Just as ultra-low measured harmonic distortion can sound sterile but doesn't here, feedback can but needn't. Hell though if I have a clue as to why, when and how come not then. It's interesting coming from tubes when first encountering the F5 in a well-dialed system that won't get embarrassed by greater honesty. While I've always known that tubes introduce 'pleasing distortions' (the main challenge finding machines that do this subtly enough to flavor, not become headline intruders), Nelson's FirstWatters from the F3 on have caused some head scratching and second-guessing.

Particularly for midnight listening, ears keen as Spock's, lover dearest sleeping next door, the F5 stomps my SETs. At regular levels, triode tricks catch up to make their own case. For me at least, then it's a question of what flavor experience I crave. If it's a highly visual one, the transistors; if a melted heart, the tubes. I admit this commentary isn't the stuff of scales and tape measures. The level of game Nelson Pass engages these days when commercial considerations are out the window means that this brazenly subjective approach as an experiencer becomes mandatory. After all, the graphs already show us ruler-flat response with distortion so low, we'd assume it below our ear/brain threshold.

Addressed solely at us nutters in the Tube Corps, ultra-low distortion isn't intrinsically boring and uninvolving, clean as a whistle but bereft of juiciness. It's about more though than chasing textbook perfection no matter the means. This is no Halcro. Yet transistor goodness needn't mimic valve amps to somehow clone their behavior before a transistor amp can make its very own kind of magic. Depending on how your personal journey through audiolandia has proceeded, this could all be self-explanatory. In fact, you might wonder how a reviewer could take six busy years before coming to that conclusion. Um - we're not all the Silver Surfer. But Oliver Stone's "Greed is good" speech for Gordon Gecko comes to mind. How it stood normal values on its head. So the F5 could stand the aural beliefs of valve fanciers on its head; not for sounding the same but because it achieves equal validity -- arguably superior in aspects as explained, merely different in others -- via such contrarious means. 20dB of feedback. Pah. Or perhaps the very reason for the F5's sterling showing? If feedback is bad, tell that to Mr. Pass and my zero-feedback ears. Glorious confusion. Or as Gurdjieff is rumored to have muttered under his last breath: "You're all royally screwed now".

Curtain time. The F5 brings the Nelson Pass sonics explored in the present FirstWatt range to 25wpc needers with enough gumption for 2 ohms. Be aware though that 15dB of amplifier gain isn't very much. To serve up 90dB speakers in style, you'll want 20 - 25dB in your preamp . Not that those are FirstWatt's focus. But the F5 could be a back-door opportunity for those not subscribed to the hi-eff religion. You'll simply no longer be running the amp inside that first watt where its distortion drops off the map. Nelson predicted that some listeners would like the F5 best of the bunch. I certainly see why. As much as an audiophile floozie can at any given day, I might just share that opinion in fact. It's unmistakably the most universal FirstWatt yet, with the high-power 'muscle' versions of F3 thru F5 already announced to welcome those with even harder-of-hearing speakers into the fold. Consider this SET freak deep inside the fold already. The old Zen master is cooking and with his latest amp, even cavemen and Geico customers are reportedly capable of rolling their own. What a gift to the DIY community - and those of us reluctant to inhale solder fumes. Thank you, Mister Pass! ... who, it is only proper, shall have the last word on this matter:

"How do these effects come about? I really don't know. My experience so far is that good ideas, technique and philosophy all help but you have to build things and play with them at length, and if you can't hear or you don't put in the time, then you're out of luck. Edison was right - invention is 10% inspiration, 90% perspiration."

Quality of packing: Stout card board with solid foam base and foam corners.
Reusability of packing: At least once.
Ease of unpacking/repacking: Very easy.
Condition of component received: 100%.
Completeness of delivery: Amp and power cord.
Quality of owner's manual: Not completed at time of delivery, tend to be well-written white papers with performance graphs, application notes and humorous Pass-style common sense.
Warranty: 5 years.
Human interactions: Prompt, friendly and professional.
Global distribution: Two or so US dealers serve as world headquarters for sales.
Pricing: Very fair.
Special application conditions: Low gain perfect for hi-effers. Enough power and drive for many standard speakers but then extra gain will have to be handled by the partnering preamp. Sounds best after one hour but don't leave on indefinitely as the amp runs in class A and thus, hot and heavy.
Final comments & suggestions: Think Nelson Pass overlooked something I'd spot? Not.
FirstWatt website