One-owner Krell Evolution 505 CD / SACD player in better than new (9.5/10) condition. We sold this unit to this customer, and it has recently been overhauled (over $2,100) by Krell with a brand new CAST output board, CD / SACD drive gear, and fully calibrated by Krell - just like new. There's not a single ding, scratch, scuff, or dent to be found anywhere. Price does NOT include PayPal fees and actual shipping/insurance cost. Over a decade of 100% positive feedback, I ship the same day I receive payment. We are authorized Krell dealers.
The Evolution 505 is massive for a CD player: 29 lbs, a half-foot high, nearly a foot-and-a-half wide and deep. The aircraft-grade aluminum chassis, which comes in silver or black, has rounded edges and slitted sides that give its bulk a streamlined grace. Like the power and preamplifiers in the Evolution series, the 505 incorporates Krell's proprietary CAST circuitry, and therein lies much of the reason for its cost. . . and that payoff I mentioned.
Krell's proprietary Current Audio Signal Transmission (CAST) circuit manipulates the audio signal in the current domain instead of in the typical voltage domain. It does this in the circuits within a component, and also—through CAST outputs—the connections between components. Of course, to go this route, you'd need a Krell preamp with CAST inputs (more on that later).
In theory, this approach has two advantages. First, the signal doesn't have to be converted from current to voltage and back to current; it flows as one continuous stream of current. Second, whereas signals in the voltage domain go from low impedance to high impedance, signals in the current domain go in the opposite direction. As a result, factors that inevitably corrupt an audio signal—stray capacitance and inductance on a circuit board, unpredictable effects caused by mismatched impedance of interconnect cables, and so on—are said to be dramatically reduced, if not eliminated.
One drawback of operating in the current domain is that, watt for watt, it requires twice as many transistors as the voltage domain. This means that the component must be bigger and heavier, and run hotter—and, consequently, will cost more to build and to buy.
There are other reasons for the high cost. Most visibly, there's the damped chassis of aircraft-grade aluminum; the transport itself sits on a rigid subchassis of the same material. The disc drawer is mounted on a steel plate to maximize disc-reading accuracy. There are also two discrete sets of anti-aliasing filters: one for CD, one for SACD. All circuits run in class-A, with separate output stages for CD and SACD. There are two linear power supplies, one for the digital circuitry, one for the analog, each with discrete regulators and heavy toroidal transformers to control the pattern of radiation. Three Burr-Brown PCM1738 DACs, each capable of handling 24-bit data at a sample rate up to 192kHz, are employed, two for SACD, one for CD. And a fairly new anti-jitter circuit, retrofitted since the first units came off the production line, is said to reduce the already-low rate of jitter between the transport section and the DAC by a factor of five (again, more on this below).
Back to CAST: The advantage of manipulating signals in the current mode is that it allows for much wider bandwidth. Dan D'Agostino of Krell tells me that, while signals in the voltage domain can achieve a bandwidth of about 300kHz, the Evolution 505 has a bandwidth of 1MHz.
Does this matter? CDs encode data up to 22kHz, meaning a CD player doesn't need more than a bandwidth of around 44kHz to operate. But because "brick-wall" anti-aliasing filters are difficult to manufacture and optimize, manufacturers long ago made use of oversampling to increase the signal bandwidth, and thus allow for smoother filters and lower distortion. The DSD encoding used on SACD has a bandwidth of 100kHz, which is thought to be the main reason the best of them sound so good, so "analog-like." But 1 megahertz—ie, 1000kHz? Is that overkill?
Dan D'Agostino says no. The more bandwidth, the less noise; the less noise, the greater detail, depth, and transparency in the music—a relationship that holds, he insists, at least all the way up to 1MHz. I have no way to evaluate this claim scientifically. All I can do is listen.
I did all of my listening through Verity Audio's Parsifal Ovation loudspeakers and Krell's own FBI integrated amplifier, using the latter's CAST inputs and, for comparison, its balanced inputs. Though I didn't have it on hand, I once spent a lot of time with the Evolution 505's non-CAST predecessor, Krell's SACD Standard (some of that time hooked up to the FBI and the Parsifals), with which I was able to make rough comparisons. Cables in all cases were by Nirvana, except for the special, 4-pin, bayonet-connector CAST cables, for which I used Krell's own and, toward the end of the listening, Nordost's. (I think those are the only two makes on the market.)
I placed the 505 on three Black Diamond Mk.IV Racing Cones (which, as they do with most electronics, tightened transients somewhat), and plugged the 505's power cord into Bybee Technologies' Signature Model Power Purifier, as well as straight into my hospital-grade wall sockets (the FBI is always plugged straight into these), which are wired to a dedicated 20-amp power circuit installed long ago by an electrician, and still, by far, my most cost-effective audio upgrade.
In Stereophile's 2008 Buyer's Guide, I wrote a minute-by-minute account of all the details a really good system should reveal of David Zinman and the London Sinfonietta's recording of Górecki's Symphony 3 (CD, Elektra Nonesuch 79282-2). If I'd had the Evolution 505 at the time, at least as it's since been modified (see below), the article might have been a good bit longer. It let me hear more vibrato in the bass strings, more attack and bowing on all strings, a more percussive edge on the piano. There was also more modulation in soprano Dawn Upshaw's voice. If dynamic gradations can be visualized as a dot-to-dot diagram, the Krell seemed to insert a few more connecting points between each dot; that is, it let me hear subtler differences in decibels. This was no small matter; these fine variations help weave the illusion of a human being behind the voice or violin bow or drumstick. In other words, the Evolution 505 gave me a clearer sense of that human presence making the music.
When I played Michael Tilson Thomas and the San Francisco Symphony's recording of Mahler's Symphony 9 (SACD, San Francisco Symphony 821936-0007-2), sounds popped out all over the soundstage, very precisely but in full harmonic richness; just before 4:00 in the first movement, the reprise of the theme came through very clearly and movingly under the blaring horns—much more so than through other gear.
On "Tangled Up in Blue," from Bob Dylan's Blood on the Tracks (SACD, Columbia CK 9032), an extra octave of air seemed to rise from the steel-string guitar. This fizz, clearly a product of the guitar's harmonic overtones, matched the guitar's rhythm; it wasn't just a vague whooshiness.
In every sonic dimension, at every checkpoint down the list, the story was the same. Width was wider, depth was deeper, imaging was sharper—but, unlike some gear that excels at all these audiophile virtues, the Krell 505 sacrificed nothing in musicality (for want of a better term). Johnny Hodges' saxophone, say, on Duke Ellington's The Far East Suite: Special Mix (CD, RCA Bluebird 7863-66551-2), was purringly lush without losing any of its brassiness or reediness. Dizzy Gillespie's high notes on Max+Dizzy: Paris 1989 (CD, A&M CD6404), his startling duet recording with Max Roach, blared without diminishing any of his trumpet's burnished glow. Instruments of all sorts sounded like themselves; the differences between a violin and a viola, a Steinway and a Bösendorfer, steel-stringed and nylon-stringed guitars—spinning faithful recordings, the 505 let me hear these differences as clearly as if I'd heard live.
Earlier in the review, I mentioned that Krell upgraded the 505's anti-jitter circuitry after production got underway. My review sample was one of the early units, so in the middle of the reviewing process, Krell installed the new circuit in my sample. I could immediately hear an improvement. Everything sounded more coherent. Paul Motian's brushwork on Bill Evans' Waltz for Debbie (SACD, Riverside/Analogue Productions CAPJ-9399-SA) was rhythmically tighter, the bristles snapping against the snare; I could hear the wires rattle. In the Górecki, I could hear much more counterpoint, and back and forth, between the string sections.
Bass, always a Krell strength, was also improved. Donald Fagen's Morph the Cat (CD, Reprise 49975-2) begins with two bass lines, one much deeper than the other. Before the anti-jitter mod, the lower bass line had some overhang and sounded a bit boomy. After, it sounded both deeper and tighter—no overhang at all.
In general, music became more intricate and lively with the new anti-jitter circuit. If you bought an early unit of the 505, get the upgrade—it's free. (Check your software menu; if your player's version is higher than 1.0, it includes the upgrade; if you're uncertain, call Krell with the unit's serial number.)
I was very recently sent a further upgrade—a new CAST interconnect cable. In the beginning, Dan D'Agostino sent me a 1m length of Krell's own silver-conductor CAST cable. More recently, though, he'd sampled a strand designed by Nordost, using their own proprietary Micro Mono-Filament Technology, which employs four silver-plated 99.9999% OFC conductors. The Nordost costs a lot more—$1600/m vs the Krell's $400/m)—and, I regret to say, it sounded better. The backdrop, which I'd never considered noisy, got quieter and blacker still. (Low-level noise is like that; you don't hear it till you don't hear it.) Massed strings got warmer, back-row horns or drums receded farther to the rear, and the entire front end of my living room, around and behind the speakers, seemed more saturated in sound—all with no loss of clarity or detail. The new CAST cable didn't make as big a difference as the new anti-jitter circuit, but it made a difference—and, again, it wasn't subtle. Alas.
A question that's often raised about ultrafine CD players: Is it as good as analog? I compared the SACD and the LP of Bill Evans' Waltz for Debbie, both pressed by Analogue Productions. Overall, the LP won. Paul Motian's ride cymbal was more three-dimensional, its ring zingier; Evans' piano had fuller harmonic overtones. On the other hand, Scott LaFaro's bass was a tie, though the Krell might have revealed a tad more detail. In any case, it was very close—closer than any other such comparison I've ever done.
CAST vs Balanced
A significant caveat: All the listening I've described so far applies to the Evolution 505 with its CAST output carrying the signal. Whatever the rest of your system, the signal will remain in the current domain inside the 505; but if your preamp lacks CAST inputs—that is, if it's not a fairly recent Krell model—the signal switches to voltage domain once it passes through the 505's balanced or single-ended outputs.
Krell acknowledges that the Evolution 505 was optimized for CAST, and was designed to be the signal source of an all-Krell—preferably, all–Krell Evolution—system. Without the CAST circuitry, the 505 would have been smaller, lighter, and cheaper. So, the $10,000 question: How did this thing sound through its balanced outputs?
In A/B comparisons—which I could do very easily by switching the input on the Krell FBI from CAST to balanced and back again—the differences were substantial. It would go too far to say that switching to balanced was like throwing a sheet or blanket over the soundstage. But it was as if the klieg lights had been dimmed by several watts. On Dylan's "Tangled Up in Blue," the guitar's overtones were still there, but they didn't sparkle; the snare drum didn't crackle and snap; Dylan's voice was a little bit flatter-toned. But remember, this was in comparison with the sound of what might be one of the world's greatest CD players in its optimal mode. In its avowedly less-than-optimal mode, the 505 still sounded superb—just not as superb. John Atkinson will probably note that his measurements apply to the balanced and/or single-ended outputs. I don't know what he's come up with, but the Evolution 505 may well measure better through its CAST outputs.
Through its CAST outputs, the Krell Evolution 505 is the best CD player I've ever heard in my house—maybe the best I've ever heard, period. I found its sound jaw-droppingly superb.
Bottom line: If you don't have a Krell preamplifier or Krell FBI integrated amp and aren't intending to buy one, the Evolution 505 is still an excellent CD and SACD player—give it a listen—but you won't be hearing anything close to what this thing can deliver. However, if you're considering going the full CAST route, and if your bank account can handle it, then this may be the one.
My bottom line: My bank account can't handle it. I bought the 505 anyway.
20 Hz to 20 kHz +0.0, -0.5 dB
Signal to noise ratio
“A” weighted 105 dB
20 Hz to 20 kHz, -82 dB
Analog Audio outputs
1 pr. CAST via 4-pin bayonet connectors 1 pr. balanced via XLR connector
6 single-ended via RCA connector
Digital Audio outputs
1 S/PDIF via RCA, 1 EIAJ optical via TosLink
1 Wireless IR Remote
1 Remote IR sensor input via
a 3-conductor 3.5 mm connector
1 RS-232 port via a 9-pin D-subminiature connector 1 12 VDC trigger input via 3.5 mm connector
1 Krell CAN Link via an RJ-45 connector
1 12 VDC trigger output via 3.5 mm connectors 1 Krell CAN Link via an RJ-45 connector
17.3 in. W x 6 in. H x 17.3 in. D
43.8 cm W x 15.3 cm H x 43.8 cm D
Shipped: 37 lbs., 16.8 kg Unit only: 29 lbs., 13.2 kg