Fantastic “Mini” system with nicely matched Pro-Ject Pre Box RS Digital acting as fully featured Pre+DAC+Headphone Amp and AmpBox RS as power amp. Relatively small stature of this system is certainly masquerading the fact that I’ve managed to drive some difficulty speakers with zero problems. Amp Box RS is based on Hypex UCD amplification modules and custom built (and quite unique) valve input stage/buffer. As mentioned, it’s quite capable amp quite suitable for most domestic speakers and end even tough loads.Combination of ClassD amplification and valve input stage does introduce certain finesse and overall smooth character to the amplification quality and overall sound signature. As my power amp over usage was quite light, there is still plenty of life left in the valves itself. Pre Box RS Digital is really unique offering as user can switch between the DAC chips (dual mono Burr Brown PCM1792 or single Burr Brown PCM 5102) and between the valve and solid state output stage! DAC is DSD compatible and USB implementation is quite good as I didn’t have a need to use custom USB digital converters. Headphone amplifier is operating in Class-A and I find it excellent and quite usable actually. It’s really feature rich offering and rarely you can find the DAC with 5x Toslink and 2x Digital RCA inputs! I did use mostly Solid State section with PCM1792 chip circuit in place, so in that respect valves are not used much, if at all, so plenty of life left in them. Condition is excellent, really light and faint marks on the AmpBox RS side and tiny one on the Pre Box RS Digital top cover but honestly nothing visible from the front and actually barely visible in general. I do have original boxes for both devices and free next day UPS shipping offer is in place for this listing.