Sony's second consumer d/a converter, much refined version of the original DAS-702ES, and companion of the CDP-553ESD integrated player.
Strangely, though, Sony still didn't use its own d/a ICs nor Philips' but Burr Brown's... the same as in the CDP-553ESD.
The 703ES has two Burr-Brown PCM-53JP-I-K d/a chips teamed with Sony CXD-23034 digital filters, CX-23053 C-Mos LSI for demod' + sync and 7th-order Butterworth GIC-type LPF.
The above is all like a 702ES but added was optical transmission with photo couplers between digital and analogue stages for less noise, less distortion and cleaner grounding.Also refined were the current to voltage conversion circuits. The output stage kept the PNP/NPN high-fT pairs system but used here dual FET cascodes in its first stage and MOS-Fet buffers with large current capacity.
Hardware-wise, this remained typical 1980s Sony : copper bus bars and heat sinking, LC-OFC wiring (99,995% purity), a total of more than 33,000µF of ELNA for Audio, ELNA Cerafine and metal film capacitors, one bigga 190V toroidal trafo for the analogue stages plus another slightly smaller toroid solely for the digital stages ; the PCBs were also upped in quality, along with ceramic powder-damped electrolyte added in the capacitors and gold-plating used on the carbon resistors' caps.
The chassis, although only partly copper-plated, is made of 3mm / 4mm aluminium slabs (top & sides, respectively) plus 10mm & 15mm aluminium structuring corners ; all non-magnetic.
The stands were upped as well with a slab of rubber glued onto massive ceramic powder feet.
Three digital inputs and one output are provided, one of which was made for the soon-to-happen DAT digital recorders ; that supplementary INput is linked with the sole (digital) OUTput and both are activated not by the input selector but by the small "tape/source" switch which is, by the way, the only visual difference separating the DAS-702ES and the 703ES.
As noted by many, the amazing sound quality results not so much from the technologies used but by the care and absolute perfection in build-quality and choice of components.
That's very Sony, be it in the pre-Esprit, ESPRIT or R series : we're in this for the music, not the technical tour-de-force or outer-space specifications : like a TA-E88B, a TA-N902 or a TA-ER1, the 703ES reproduces
l i v e m u s i c.
The 703ES gave way to the DAS-R1 masterpiece, the DAS-R1a über-masterpiece and the DAS-R10 best-ever-masterpiece.
Make that magnificent stock.
A real 703ES here ; nudies of a (modded) USA 703ES here.