Krell SBP-64X DAC and Power Supply

For sale, we have a the classic one owner Krell SBP-64X DAC with its separate power supply.The 64X features custom made KRELL DAC's from scratch, custom circuit, DAC's, oil and Teflon caps, custom power supplies and transformers. The SBP-64X process red book (44.1k) 64 times to smooth out and improve digital playback. The original owner who is a client of ours, was very meticulous, and did a ton of research on all the items that he purchased. Included in the sale is the original owners manual, owners reference booklet, review article, and hype sheet for the unit from Krell. We purchased a complete system from our client, and this along with the other pieces were in constant use since he purchased them new. Never abused, and thoroughly enjoyed, all the gear was well cared for. 

This 64 times oversampling digital processor is in perfect working order, and very good physical condition. On top of the unit there are some light scratches and some blemishes, including some round circle mark from the power supply resting on it. There is also a mark on the right side edge of the  faceplate. On the power supply, there is a light scratch on the right rear side,and minor blemishes. There are  no deep scratches and no dents. The unit presents itself very well. Please see pictures for further details.

We don't have the original box for this unit, but we take packaging and shipping seriously. We spare no expense and use a heavy duty box, several inches of polyethylene foam on all sides of the unit, and use water activated, fiber reinforced tape on all seams. 

hi-fi News review:

SPB-64X Technology
This unit comes in two boxes, the plainer black-enamelled steel one housing the power supplies, which should be located remotely from the player. For the processor-decoder unit, the electronics are divided into two sections with two separate PCBs, one for digital and the other for D/A and analogue.

Following amplification, the presence of either an optical or a wired digital input is sensed before it is linked in via logic circuits. Good headroom is claimed by virtue of the 24-bit data-path employed, while the DSPs have generous 56-bit accumulators for computation, so avoiding the need for scaled processing which can occur with low-accuracy over-sampling digital filters.

With a 64x resampling rate, little filtering is required, since in theory the bulk of the aliasing and spurious noise artefacts will lie above 2MHz and may be easily dealt with using simple low-pass analogue filtering. It is hard to find multibit DACs that can operate at these high speeds, thus Burr-Brown PCM 64P units were chosen, one for each channel. These have a high-speed parallel digital input facility, while a multi-turn adjustment is provided for phase alignment of the DAC linearity.

All circuitry following the DACs is discrete, and consists of a current-to-voltage converter, passive filtering and de-emphasis, followed by transformerless balanced output amplifiers, all these circuits working to Krell 'Class-A' principles. The output is DC-coupled, servo- controlled, and has relay protection.

Sound Quality 64X
Having experienced most of the CD heavyweights, I can state that the 64X is capable of the finest digital replay I have heard in respect of models I have reviewed in these pages to date. You cannot mistake the essential Krell character running through the sound of this digital decoder. The reproduction was highly confident, stable and well founded on excellent bass, the latter easily capable of driving the best Krell-based systems to their maximum LF performance potential. Stereo stages were rock-steady, the sound was dynamic, and above all 'powerful'. In this manner, the 64X defined the available state-of-the-art.

Looking at specifics, stereo focus was strikingly precise, throwing soloists into clear relief and never confusing them with the backing, whether it be a multi-tracked rock chorus or a full classical orchestra. Both perspective and stage width were also excellent, while depth rates were very good. Here, the 64X sounded as if the last few decibels of dynamic range were being muted, and while it generally recovered air, ambience and recorded acoustic accurately, sometimes you were left with a hint of dryness in the overall effect, a slight tinge of anechoic-sounding sterility. Nevertheless, I suspect that only the most transparent of reproducing chains will be capable of revealing this characteristic.

More obvious was the rather characterful treble, which has a certain contrived, excitable nature – although it was undeniably excellent. It sparkled, perhaps excessively so, yet had superb resolution and clarity. Perhaps 'too good to be true', the treble was a shade 'zingy' and exaggerated, though the effect was neither seriously unmusical nor fatiguing.

No Jacket Required
In general terms, the midrange was first-rate, despite a tinge of 'solid-state' hardness which added an extra force to the presentation. Essentially neutral in other respects, the mid sounded both powerful and dynamic. Lead singers sound as if they have been released from a straitjacket and appear to deliver with greater expression and articulation than noted on designs I have reviewed previously.

Listening to the 64X was no mere duty – it was a pleasure. The high levels of detail and resolution evident continued right down to the lowest bass extreme, and here the DAC powered along, showing a remarkable sense of scale and authority. The bass performance had real slam and was most revealing, but the magic was worked over a whole range of programme material, both rock and classical.