The Live Wire Solutions SPDI is a passive direct input box that can be used either in the studio or on the stage. My experience using the SPDI has been only in the studio, although it's certainly suitable for use either way. The box has an XLR output on one end and two 1/4" jacks on the other for input and through. It's not rack mountable as it's floating box.
It's not hard at all to learn how to use the Live Wire Solutions SPDI. It's just a simple DI box with only a few features to be aware of. The box has two switches - one for a ground lift and one for an attenuation pad that can be set to either - 20 or - 40 db (or flat or course). Beyond making your basic connections, that's all you really need to know, so a manual shouldn't be necessary.
While I wouldn't say that the sound of the Live Wire Solutions SPDI is anything to write home about, it more or less stays true to your original signal and is fairly flexible in helping you to achieve the sound you're after. I've only used the SPDI to record keyboards and synthesizers, and for this application it does a find job. For the price, you really can't say anything too bad about the sound as it's certainly adequate and is better than most DI's in the price range.
While not my number one choice for a DI box, the Live Wire Solutions SPDI is still a very solid choice, especially considering the low price. It's probably best used for live sound since it's cheap and can afford to be throw around a little bit, but having only used it in the studio, it's good either way. This is about as cheap as you'll find a DI box, so definitely check it out if you're on a budget and want a nice little DI for your home studio or otherwise...