Pro-Ject Pre Box RS2 Digital - Pre-amplifier, DAC, headphone amp

This is a stellar piece of kit to build a system around. The Pre Box RS2 digital is a very high quality unit combining a pre-amp, DAC and headphone amp into a very versatile package — which also includes a toggleable tube stage.   
This mint-condition unit comes from a smoke-free environment, includes all accessories, and the original box. I also have some spare tubes, and the matching tiroidal power supply upgrade, as upgrades to the sound of this unit even further if you're interested!   
Manafacturer Description  The Pre Box RS2 Digital is the bigger brother of our award winning and ground breaking Pre Box S2 Digital. It uses the same excellent sounding DAC chips as the S2 version, proving once again that the Pre Box S2 Digital was already at the very top of high-end DACs and absolutely beyond its competition. Based on the same core-design principles, the feature set is extended and driven to new heights. The result is a fantastic sounding and very versatile box. The perfect partner for the cream of the crop of high-end amplifiers and speakers alike!

Specifications  DAC:  2x ESS9038Q2M (dual mono - 32bit/768kHz/DSD512)
Digital inputs: 1 x USB 2.0 Audio 32/768 + DoP and Native-DSD up to DSD512 1 x HDMI I2S for CD Box RS2 T    2 x S/PDIF optical 24/192 1 x S/PDIF coaxial 24/192 1x AES/EBU balanced 24/192
MQA Support:  full MQA unfolding by hardware
Line-level input: 1 pair XLR 1 pair RCA 
Input impedance: 15 kOhm 
Output impedance: 180 Ohm solid state, 220 Ohm tube 
Analog outputs: Pre-out (XLR & RCA), Headphone (6.35mm jack) 
Headphone output power: 90 mW / 300 Ohm; 245 mW / 32 Ohm; 90 mW / 8 Ohm THD+N (20Hz - 20kHz): < 0.006% solid state/0.017% tube @ 2V RMS, 1 kHz 
Masterclock output: 16.9344MHz for CD Box RS2 T 
Bluetooth Version: Fully embedded Bluetooth v4.0 
Bluetooth Codecs: SBC, AAC, AptX 
Output Buffer: discrete and balanced, tube and solid state
Tubes: 4 x 6922EH Power supply: 20V/3A DC, 110-240V/50, 60 Hz 
Power consumption: max. 1.2A DC, <0.5W in standby  
Dimensions (WHD): 8.1" x 2.8" x 8.7" Weight: 3.8 lbs.