SONY SS-GR1 + TA-NR10 + TA-ER1 + CDP/DAS-R10

Ultra Ultra Ultra rare. The only real Hi-End audio system from SONY. 

SS-GR1 Speakers
The original (and only) R1 loudspeaker : massive yet extremely refined. Refined because hidden at the back of the top horn load is a Bio-Cellulose super-tweeter ; the tweeter and mid drivers are based on silicon carbide (SiC) as used in the x-rare SS-G777ES while the woofer and mid drivers are based on a carefully matched mix of polyamide fibers and pulp, as first used in the abovementioned G777ES.
Bio-Cellulose is an extremly thin material with superior stiffness and a resonance peak placed extremmely high above its frequency range of use. It is technically better than Beryllium or anything else. Bio-Cellulose is threaded by bacteriae and was originally used in the SS-A5 (1989), the ultimate SS-G55 series as well as in the MDR-R10 reference headphones.
The three CD horns (Constant Direcivity) are directly carved into the multi-layer enclosure ; the shape of the horns was calculated from the driver's radiating specs : laterally to reduce outward pressure and listening rooms' reflections, vertically to reduce interference between drivers.
The enclosure is a two-in-one : a basic rectangular frame making the sides, top and bottom supports the real enclosure made of carved multi-layer wood
In fact the GR1 can be seen as the cost-no-object result of the efforts spent on the late 1980s Voce and "G" series. Unfortunately, at 2,200,000¥, a pair of SS-GR1 was a luxury only the outrageously rich could afford. The only ones spotted outside Japan bear the #200 043 and #200 044 serial numbers - these are Sony Japan serials. There is another pair (B-stock) which was sold to an employee in France for a few hundred euros ; it is supposed to have spent the past ten years rotting away in a damp cellar around Paris...
It took the engineers almost four years to finish the GR1. And then it got a Golden Sound Coty Award, the highest in Japan, alongwith the Yamaha GF-1.

TA-NR10 Mono Power Amps
The last R1 / R10 component to appear, as developped by the team that crafted the other R1 units.
The SS-R10 high-end electrostatic loudspeakers appeared even later but that was more of a one-man project launched by Keijiro Maeda and finished by others when the former sadly passed away.
The TA-NR10 is in fact an updated and ameliorated TA-NR1 : bigger, heavier, fully (gold-plated) MOS-FET equipped, 6N OFC wiring, dual-layer 70µ OFC copper circuit paths, OFC power cord, high-carbon steel chassis, Germany-sourced super-permalloy core line transformers, brass terminals, 10kg / 1kVA toroidal core transformer, 25A diodes. Etc.
The enclosure is made of 2,1cm extruded aluminium and, last but not least, the heatsinks are made of pure copper - 10kg each !
Unfortunately, unlike the original TA-NR1 which sold fairly well worldwide, the NR10 were on order only, much more expensive and are now complete unobtainium.
If the R1 and R10 units gradually vanished from the catalogs throughout the mid to late 1990s, Sony kept them in fact still available in Japan on order only : dedicated service and spare parts were available as well until at least 2002 or 2003.

TA-ER1 PreAmp
The absolute preamplifier, a b s o l u t e.
Reviewed in Japan above the contemporary Mark Levinson, Krell and whoever else that was more trendy, had more "aura" or good press agents. Only the Pioneer Exclusive C7 and the Cello were ranked better, both by a very small margin. That's the league the TA-ER1 was playing in - it still is, up there, at the very top.
If very different, the basic engineering has the same perspective as that of the Exclusive C7 : no super-extra-sci-fi circuits potted in mysterious modules but plain common-sense carried out with ultra build quality.
Extremely high impedance inputs High-efficieny FET with 4MOhm resistance line inputs to reduce voltage loss and keep input current stable, input signal level's variations notwithstanding : less distortion, no signal loss, better if not perfect driving of the following stages.
All-balanced signal treatment All-balanced even for the unbalanced inputs to amplify the signal between hot and shield only but not the ground electric potential at chassis. The unbal inputs therefore have three-point connections as well : hot, cold and ground, the latter derived from the cold point. This also allows the electric potential of ground to not fluctuate even when input sources are connected or disconnected.
Carbon conductive resin attenuator Apparently custom-ordered from here (yes, ALPS, who else ?), this 3x 30kOhm attenuator has a total range of 130dB, a gang error of 1dB down to -100dB (±0,5 to -60dB). It is entirely gold-plated, brushes included.
This attenuator is housed in solid brass slabs of 9,5mm thickness and is remote-controllable with a supersonic ceramic motor which remains entirely separate from the attenuator itself ; its processor disengages itself entirely one second after having been used. A smaller variant of that attenuator, again custom-ordered, was used in the TA-E1 and the original was also used by Technics, Accuphase, Micro and a few others (and a bigger one in the Luxman CL-88).
The other features, in no particular order, are ultra-low impedance MOS FET Direct SEPP output, transformer-balanced MC input, entirely dual-mono and two-tier circuit boards for ultra-short wiring and heat repartition, a separate power-supply with a bigga low-leakage toroidal transformer and copper-shielded high-quality ELNAs, dual-sided relays for all signal points, 6N OFC wiring for all signal, power-supply and ground lines, copper bus bars and shielding, a "low extend" attenuator switch - and then some. Read the TECH1 section and Knobber images #6 and #10 to #16 for the details and the rest !
Visually, the ER1 was designed by Yuuji Morimiya.
The production run is supposed to have been of 100, mainly on order but the highest serial spotted so far however is the japanese #200 185 so the total worldwide count should be of 200 made, of which about 25 were original 230V / EU models. A particular Sony twist, the serial number isn't on the TA-ER1 itself but on the RPS-ER1 power supply.
Many TA-ER1s were discounted to "insiders" and Sony employees as late as 2000/2001, all with ridiculous B-stock prices, three years after distribution had stopped in Japan.
If the TA-E88B is one of the best preamplifiers of the 1970s (and one of the best - period), the TA-ER1 is the best preamplifier the history of 2-Channel audio will have ever heard. Since that history is now closed, Sony or otherwise, the TA-ER1 naturally is even more desirable.

CDP/DAS-R10
Launched for the 10th anniversary of the CD format, the DAS-R10 is like a DAS-R1a but pushed to the limit. Price-wise as well : four times more expensive !
The system inside is based on Pulse length Modulation (PLM), converting voltage to current at 50MHz high-speed to avoid voltage supply fluctuations and noise plus the proximity between voltage feeding the ICs and that of the signal itself.
The conversion is done by two circuits (one for each phase) right from the input start point and so the rest of the signal remains entirely balanced - this is close to what was applied to the other absolute masterpiece, the TA-ER1.
With the help of another circuit (CIV) placed after the actual d/a section, this also reduces distortion and noise globally and at the low-pass filter ; the CIV was designed for excellent group-delay characteristics for maintained phase accuracy.
Eight 24bit 168dB stopband attenuation DSP ICs deal in parallel with oversampling and interpolation ; they are also in charge of playing with the output filter's roll-off slope, as carried later on in the CDP-XA55ES or CDP-X3000.
All processing nodes are physically implemented on metal core modules (as later on used in the TA-E1 and TA-N1...) which are heat-resistant aluminium alloy pads holding 4-layer copper patterns on which SMD components are placed. No IC-induced electrical noise, no wiring, better thermal conductivity and minimal signal paths.
The production run was set at a bit more than one hundred but the highest s/n spotted is the japanese 200 175. 
The CDP-R10 Received not only a COTY Award but the Golden Sound distinction for 1993 ! Quite a few other awards, too, but as for many other superlative Sony units... nobody knows about it. Or nobody is willing to.
The CDP-R10 drive took on a very old idea : the Fixed Pickup Mechanism - introduced by Sony in... 1982 in the first commercially available CD player (CDP-5000), reintroduced here and later in 1994 with the CDP-XA7ES and CDP-X5000 and later again in the SCD-1 and SCD-777ES.
Unlike the later (smaller) FPMs, there is a diecast aluminium alloy platter on which the CD resides (upside down) ; the drive's codename is "CDM26" and it has a lens tracking range of ±50µm. The extruded aluminium rails on which it is magnetically driven are finished with 1µm ; the motor is a 3-phase BSL ; the laser-block itself is the KSS-332A.
The back holds the following outputs : 1x BNC for DAS-R10 sync, 1x BNC, 1x RCA, 1x AES, 1x optical (TOS), 1x optical (ST), and the Twin Link, the latter in upgraded "S" version.
Dedicated switches are simple on/offs for each digital output with only the Twin Link and sync BNC that cannot be switched off. The two left switches are for the Twin Link : on/off and sync with the DAS-R10 through the BNC, AES output or no sync at all.
The front display surprisingly uses an LCD screen instead of an FL or DotMatrix - LCD displays are supposed to not radiate bad waves onto the surrounding electronics... The last pre-production sample had a vertical opening through the lid - like a CDP-5000 :)

These penultimate R10s were launched as a commemorative items to celebrate CD's 10th Anniversary so, at least, here, this new / old / new surprise makes sense. The production run was set at a bit more than one hundred but the highest CDP-R10 s/n spotted is the japanese 200 212 ; we can therefore assume a total/world run of less than 250.
At 2,000,000¥ with the DAS-R10, Sony made these as showpieces available on order only. The CDP and DAS-R10 thus did not put to oblivion the previous CDP-R1a and DAS-R1a and both combos remained available together for a couple of years.
Like the TA-ER1, the DAS-R10 and CDP-R10 are part of the all-time absolute best audio components ever made and we all want them.