I needed a Pre Amp with balanced outputs and started looking at the Pro-Ject Pre Box RS.
The more I looked at this the more I liked it and the rest of the range for that matter.
This is my unit and the rear view shows it is the later version using a mini XLR connector for the DC voltage input, this is attached to a laptop style Power Supply brick. The Pre Amp is dual mono and has valve output stages, being supplied with a pair of Electro Harmonix 6922 valves. These are not the best and can be upgraded using something like NOS Russian Military spec 6N23P to improve the sound quality. The power brick is another area for upgrading and a separate high quality linear power supply, like Pro-Jects own will improve things a lot.
There are a couple of quirks that I feel should be pointed out to anyone thinking of purchasing one of these.

First - The Two RCA outputs in the top corners are not volume controlled, they put out whatever source is selected at full volume and are meant for connection to a tape recorder etc. Do not connect your power amp to these or you will get a nasty surprise when you turn on and it is running flat out. If you need unbalanced RCA output, the Pre comes with a short set of XLR to RCA adapter leads that you can connect to.

Second - Is that the RCA input-1 and the XLR input-4 have a higher gain of RCA 6dB & XLR 12dB for use with Phono stages etc. The other inputs are meant for connection to things like a DAC/CD player which have a higher signal level and require less gain, the level for these inputs is RCA 0dB & XLR 6dB. This gives quite a bit of flexibility, 0dB/6dB/12dB gain options, depending on the input you plug into.
I will report back on how the unit sounds as it burns in.