Those of us who have made the long slow journey from one to ten in terms of sound quality know that the later steps up the ladder are usually fairly small, fairly expensive, and somewhat inconclusive. But not always. Occasionally something comes along that represents a clear and definitive leap forward.
The Leben CS300XS was one of those somethings. I won’t describe the amp itself in detail, as it’s pretty well known on this site. But its performance was a revelation to me. I was hoping to step up from a theoretical nine to a theoretical ten, but I seemed to end up somewhere between fifteen and twenty. Carefully retubed, it’s a sensational match with my HD800s. Absolutely amazing, gratifying, and rewarding. Rather than list its virtues - we’d be here all day - I’ll just say that every time I listen to it I feel it would be absolutely impossible to improve on it.
But the Apex Pinnacle improves on it in almost every way - not slightly, but clearly, easily, and definitively. But note the all-important “almost” - it’s key to this comparison.
The Pinnacle is designed and built by a guy in Texas called Pete Millett, and it’s sold by Todd Green at TTVJ in Montana, at a price that’s dirt cheap compared to the car on your neighbor’s driveway. I don’t know either Green or Millett personally, but Green has been a delight to deal with, and judging by his amp I suspect Millett is like a small but precious number of guys I knew during my previous career on the technical side of the entertainment business - 100% engineer, but also 100% lunatic.
The amp is a two-box deal, and it’s tempting to see each box as an metaphor for Millett’s split personality. The power supply is utterly meticulous, superbly engineered, completely conservative, and technically bombproof. It’s exactly what you would get if the Pentagon gave someone a million bucks to build half an amp.
In the top box, floating on that meticulous 21st century infrastructure, is a two-stage single-ended triode stereo amplifier featuring a 72-year-old tube driving two 82-year-old tubes. It too is implemented with more quality, more care and more attention than I have ever seen before ... hence the existential appeal: the amp as a whole is a cautious engineer’s approach to a principle that a cautious engineer would normally run away from as fast as possible.
The second stage of amplification is provided by one PX4 tube per channel. The PX4 dates from 1928, and was developed by the English outfit Marconi Osram. There is almost no NOS market for it, and only two current replicas - Sophia Electric, and KR Electronics, both manufactured in Eastern Europe.
For some aberrant reason I always thought Sophia and KR were the same firm, and therefore the two tubes were the same, but fellow Head-Fier bdh set me straight, for which I thank him. I got a pair of KRs to compare with the supplied Sophias, and found that the Sophias sounded significantly better. I’m sure the amp was developed around them. The Sophia PX4 is a fine audio tube. It’s neutral and unstressed and linear and quiet, it has a very wide bandwidth, and it has high resolution and high definition in spades.
The first stage is powered by a single 6SN7, which is a dual triode, and one of my favorite tubes of all time. It was developed in the 1930s by RCA as the vertical oscillator and vertical sweep amplifier for early CRT screens. That was a tough, exacting job. It’s a blue-collar, working class hero of a tube. (Idle speculation sidebar: naturally at the end of the 1930s, the 6SN7 was militarized, for radar and artillery rangefinding. And if WW2 was eventually won because the Battle of Britain was won in 1940, and if the Battle of Britain was won because of radar, then the 6SN7 is also the tube that saved civilization.)
Given the relative lack of PX4 alternatives, the 6SN7 spot is the more crucial in terms of tube choice, and both Millett and Green agree that experimentation there will yield benefits. The supplied driver is the new Tung-Sol 6SN7GTB, which is perfectly OK, and there’s a new-production Sophia (in a classy coke-bottle shape) that’s better than perfectly OK, but the true riches are in the NOS universe, of which by far the best, in my opinion, is a first-round certainty for the Tube Hall of Fame: the Marconi Osram B65 variant.
Now, there’s some talk here and there on the web that the B65 is dry and bass-shy. But really, anyone who says that ... a) must be resentful about the horrible NOS prices; and b) can never, ever have actually heard one.
NOS prices for really good B65s are awful, for sure - north of $500 a pop, sometimes $700, and getting worse all the time. (I was lucky - I had a gig at a British TV station back in 1995, when by chance some updating was going on, with consequent disposal of old spare parts, and I claimed a dozen B65s, free, gratis and for nothing. Boxed up in 1964, never touched. Still wrapped in brown tissue paper that was going brittle with age. A dozen was all I could fit in my bag. I wish I’d had a bigger bag. I also got the sign I use in my avatar. Currently it’s on the wall outside my listening room.)
People who have actually heard one will tell you that in reality the B65 has world-class bass - deep, powerful, and tight - and it throws a huge, airy soundstage, as wet as you like. It’s an ugly little fireplug of a tube - pressed metal base, dirty gray glass - but it sounds like the most beautiful thing you ever heard.
(You can get about 90% of the B65’s performance for a tenth of the price by finding a 6SN7GT by Fivre of Italy. I had a couple from 1952 and they were excellent.)
I tried many headphones with the Pinnacle and strongly preferred my second set of HD800s - not the same set I use with the Leben, but a sample that has a much flatter 6k peak. I used them dual-mono through the XLR outs.
So, with the B65 and the Sophia PX4s and the #2 HD800s in place: three enduring impressions.
First, as expected, the Pinnacle does all the conventional “amp things” perfectly - awesome, beautiful, lush, generous tonality - and amazing air, by which I don’t mean treble-tilted, but more a reminder that music moves air, and that in fact most of the air is moved down in the bass regions, and that the bass is where true airiness should be found.
Second, as if for the first time ever - finally! - you hear a geometrically perfect soundstage. No cramping, no crowding, no dimensional alteration - just a large perfect sphere all around your head, five or six feet in diameter, immaculately populated with performers in the places you instinctively feel they should be. Lots and lots of space between them - even on old “wall of sound” mush you thought you knew so well - and each is fully three-dimensional in its own right.
Third, you hear no detail. None at all. This is a completely detail-free amplifier. That is, if you use the word “detail” in the conventional sense, to mean obscure, hard-to-hear sounds way back there in the murk, which you really have to concentrate on to decipher.
The Pinnacle has no murk. Each “detail” is revealed as a separate and coherent musical strand, each perfectly and clearly audible, each with its own separate architecture and narrative and reverberant ambience. The noise floor is miles behind them, like a dull steel plate, smooth and inert and not at all granular or alive.
Probably all three of these virtues stem from the absolute purity of the circuit. In direct comparison the Leben is very close in terms of the first virtue but clearly deficient in terms of the latter two. The Leben’s soundstage - which I once thought was perfect - is actually a little squashed and shallow, somewhat pressed backward against a faint seething wall of murk, and each individual sound image is noticeably deformed or contorted. And the Leben’s “detail” - while objectively excellent in its own right - feels like it’s caught in the act of struggling free of the murk ... it’s kind of halfway out, like a monster in a horror flick emerging from the slime, but it’s not yet all the way out. More like a bas-relief than a sculpture.
So what’s not to like? Why the “almost” in the third paragraph?
Well, the Pinnacle is an SET amp, and the Leben is a push-pull EL84-based design. I’m very wary of stereotyping amplifier types - even tube versus solid state - but it’s generally true that a typical SET amp and a typical PP amp will sound different in ways that can be predicted based on experience. And in this instance neither the Pinnacle nor the Leben - despite being hyper-evolved examples - transcend the flavor of their type.
Thus the Pinnacle is utterly beautiful, smooth, serene, stable, and transcendentally, spectacularly clear. Its only atypical characteristic is its tight, strong, extended bass.
And the Leben is lively, very muscular, rhythmic, and dynamic. Its only atypical characteristic is its SET-like beauty in terms of timbre.
I think the Pinnacle does music better. But ... almost all music is based on dance forms, and I think the Leben does dance better. It’s a circular argument.
I look at the Pinnacle and I see a neon sign that says “Wanna hear everything on that track?” And then I look at the Leben and I see a neon sign that says, “Wanna party?”
Choosing between them would be a wrenching decision. I would miss whichever one I gave up, very badly. But the one great thing Head-Fi has taught me is that it’s OK to have more than one rig. So I’m keeping both, and I’m enjoying both.