Although best known for its predominantly high-end, high-power amplifiers, Krell is a full-range manufacturer whose remit extends to AV equipment, loudspeakers and disc players of various types and levels of sophistication. In fact, the company produced what to many was the finest CD player of its day - the extraordinary but frighteningly expensive KPS25.

It was followed by the SACD Standard from the entry-level KAV range, which included multichannel SACD replay in a unit costing about half that of the Evolution 505, the subject of this test. That model was introduced in 2003 and subsequently revised when the original mechanism became unavailable.

The 505, Krell's third SACD player, is from the company's no hold's barred Evolution series, and adds more sophisticated in design and construction as befits the higher price. A second Evolution model, the 525, will follow soon, adding DVD-Video replay to the feature set (but not DVD-Audio). There will be a price premium, of course, but the two 500 series players will otherwise be identical.

The 505 inside story starts with the use of separate discrete power supplies, built around a 65VA linear transformer for the drive mechanism and a 45VA transformer for the audio circuits, the latter optimised for Class A operation. Both work through with several stages of regulation to give a stiff, rock solid foundation, which has always been Krell's way.

Internal signal transmission is entirely balanced and in Class A throughout, free of feedback and the internal architecture operates in current mode, with a whopping great 500kHz bandwidth. Inter-component connections optionally use the proprietary CAST (Current Audio Signal Transmission) interface as an alternative to single-ended (for stereo or multichannel) or balanced (two channels only) modes.

The science bit

In CAST mode, according to Krell, all linked components in a system operate effectively as a single component. There is only a single current-to-voltage converter stage in the whole system when used with a Krell CAST-equipped amp, minimising (Krell says eliminating) signal transmission aberrations, and effects due to cable impedance when transmitting signals in the voltage domain.

This is the first Krell SACD player with CAST, though the interface was part of the late-spec KPS25 CD player. Current mirrors operate using LED voltage references, said to result in a two-thirds reduction in harmonic distortion.

The player is equipped with PCM1738 differential DACs on each channel, and in-house designed DAC reconstruction filters. Four SACD and two CD anti-aliasing filters are available to 'fine tune' the sound.

So much for the internal nuts and bolts. Externally, the player is scarcely less impressive, with highlights including a fully machined case with no sharp edges or corners (unusual), first-class fit and finish, a very thick, solid front panel extrusion, and a case-within-a-case design.

This last includes a high level of decoupling of the mechanism to reduce microphony. This, incidentally, reduces the differences that are usually gained by mass-loading, and it looks nicer than sticking a brick on top of the box.

The controls also have an unusually good operational feel, even by Krell standards, but some may find themselves befuddled by the field of tiny buttons on the right hand side of the fascia, and curse the fully machined remote control that needs to be half dismantled before the batteries can be changed.

SACD Text is included in the player, though CD Text is not. As part of its mission to be a complete disc-playing solution, MP3 CD (and, intriguingly, also MP3 DVD discs) can be played.

To help extract the most from the 505 in two-channel mode, we hooked it up to Krell's own FBI amplifier using balanced Nordost Valhalla cables.

The FBI was then swapped with a Classe SSP-300 processor and CA5100 five-channel power amplifier for multichannel operation, and in both cases the main loudspeakers included a B&W system based on the 805S standmounts, HTM1D centre speaker and ASW825 subwoofer.

Other speakers used included a multichannel system containing five Mordaunt-Short Performance 6 floorstanders and a Performance 9 subwoofer, plus stereo pairs from Opera and Focal. The FBI clearly favoured the speakers that offered the greatest power handling capacity, allowing it to fully spread its wings.

But does the 505 really show other players a clean set of heels? One point to bear in mind is that it needs about a week to burn in before it comes on song, and it goes off the boil alarmingly quickly, as we discovered after a power cut. Under 'cold' conditions, it just doesn't want to communicate - it sounds dull and congested.