This 100% analogue, there is no digital circuitry involved at all.
And so it's perfect if you have a digital recorder: compress the signal and add the gate before you go into the digital domain and you end up with optimal use of the dynamic range in your recorder and pretty much no noise at all.

XLR and TRS input.
XLR and TRS output if i remember correctly.

Preamp, compressor, deesser, enhancer, gate. It does all of those very decently for the money, by the way.

It's a normal 19 inch 1 unit rack.

You can't get much simpler than this: compressor has only 2 settings but in 7 years i never found that a problem. Used mainly on vocals and acoustic guitars, the unit did a good job and the gate worked great.
You have to be careful with your settings or you'll bring up hiss (enhancer and compressor). The unit is not exactly silent when you turn everything up but if you stick to the preamp then there's not much you can complain about.

Never needed the manual and when i sold this on, just recently, i realized the manual was perfectly new. I doubt the new owner will need it either...

This is budget product so don't expect miracles, but if you can't produce decent results with this then you need to learn how to use it! The sound is fine, it's just not going to rival with much more expensive gear, which is obvious anyway.

The Focusrite ISA 428 is a solid-state analog external preamplifier. There are both XLR and 1/4'' inputs and outputs and has inserts for instruments on the front of it. It is a rackable unit.

While one might get lost looking at all of the knobs at first glance, its a pretty easy unit to get used to with a ton of control. It has both a fixed gain knob which you can move to certain fixed levels and a free one to adjust smaller increments for total control. I've never had access to a manual for it.

While it certainly doesn't have the warmth that a tube preamp would have, it does have a very clear sound and sounds great both with mics and directly plugged in. It doesn't color the sound too much, depending of course if you use the filters or some of the other features. If you go straight through with the preamp it will give you quite an accurate sound.