Just my 2 cents. In my experience, you will get just as much (or more) quality and mileage out of a RNP or a Chameleon Labs 7602 or a 7622 for less money. These I've mentioned, in your budget range, in particular are very suited for acoustics and vocals.

Nothing wrong with Speck. It is a good and respectable preamp and does what it claims to do. Of course there are other preamps that do the same as well as others that have a specific/colored tone to them.