When everyone was jumping on the USB mic wagon, MXL came out with one of the more sensible solutions. Their mic had a switch providing three different sensitivity settings, which enabled users to get a sensible recording level regardless of whether they were singing or playing — something that's important if you're to make the best use of the dynamic range offered by a 16- or 18-bit USB interface (which seems to be the resolution supported by the commonly available chips used in such devices).
MXL's USB Mic Mate gives you similar functionality but without the mic. It functions as a USB mic preamp for Macs and PCs, and enables you to plug in your own choice of dynamic or capacitor microphone. The Mic Mate needs no drivers, as it is recognised as a class-compliant USB device, and it retains the same Hi/Med/Low sensitivity switch as the USB microphone described earlier, as well as permanent 48 Volt phantom power (on this model — another version has been released specifically for use with dynamic mics, which has no phantom power, but offers more gain). Conversion is via a 16-bit Delta Sigma A-D chip that supports sample rates of 44.1 and 48kHz.
The interface is built into a tubular metal housing that at first glance resembles a pencil condenser mic. Closer inspection reveals a three-pin XLR input at one end and a USB connector at the other (you have to supply your own USB cable). At first I thought the device might be able to plug directly into the back of a mic, but the shroud around the XLR connector prevents this, so you'll still need to use a mic cable.
Power comes from the USB socket, so operation couldn't be simpler, and a red LED glows when the unit is connected to a USB port. There's no monitor output jack, so you'll need to record via the Mic Mate but play back through your computer's internal audio system or another audio interface. (Mac users can set up aggregate drivers that, in effect, combine the inputs and outputs of multiple audio devices, but should note that this can sometimes increase latency.)
I couldn't find any detailed technical specifications, but in spoken word tests with a typical condenser mic the Mic Mate sounded rather good, with no significant background noise. The high-sensitivity setting is suitable for this application, and for sung vocals, but if you work very close and sing loudly, the medium setting may be more appropriate.
This refreshingly simple device does exactly what it sets out to, with no fuss. The audio quality is good, but having to monitor via a different interface may create latency if aggregate drivers have to be set up. However, for recording music on the move or producing podcasts, the Mic Mate is one of the most effective, affordable solutions around.