<p class="MsoNormal">The LaChapell Audio 538S is a microphone preamp and direct input box that runs on a 12AX7 vacuum tube. The unit has a 1/4 inch input in the front and XLR in the back. This isn't in a traditional rack mount form, and I'm not sure exactly what type of rack this is designed for as the one that I've used was just out in the open on a desk.
<p class="MsoNormal">The configuration of the LaChapell Audio 538S isn't anything too out of the ordinary. You've simply got knobs for input and output and a variety of switches for phantom power, polarity, mic/line selection, and a -20 db pad. These features are generally seen on most microphone preamps, so anyone will some experience with pres should be able to catch on instantly. Even those who don't have much experience with recording and mic preamps I think will be able to understand everything, granted that you have a basic knowledge of mic pres. For this reason, I don't think a manual is necessary but can't speak to how well it is put together because I've never seen it.
The overall sound quality of the 538S is very impressive. It has a crystal clear sound while still offering a great deal of warmth and character. LaChapell Audio definitely isn't the biggest mic pre manufacturer, but sometimes it is these smaller boutique companies that make some of the most well made pieces of gear. I've used the pre for recording vocals and drums, but hopefully I get a chance in the future to use this again because I'd love to try it out on some more instruments because I really think that this is versatile pre that is capable of being used all over the place. I don't think too many engineers will have any complaints about the way the 538S sounds.
For a piece of gear of this stature, the price of LaChapell Audio's 538S is very reasonable. While it may be out of the price range of most home studio owners, if you can get your hands on one of these you should definitely take advantage of using it while you can as I know you'll be happy that you did. For those that can afford the 538S, I would say that it is definitely a good investment as it gives you a top of the line mic pre and DI box that is extremely well made and should last a lifetime if treated right...