Keppy's Synthesizer

Keppy's Synthesizer is a lightweight yet highly configurable MIDI driver for Windows designed after the popular BASSMIDI Driver.
In fact, the main focus behind this utility was to make it meet the demands of any professional sound engineer.  This said, if set up correctly, this synthesizer can achieve very low latencies to a degree of 1 millisecond.

Straightforward installation process

Apart from making sure that .NET Framework 4.0 or later is installed on your computer, deploying this piece of software should be quite straightforward, mainly thanks to its streamlined installer.
Upon first launching this utility, you are met by a simplistic and non-impressive user interface (especially if you compare it with the UIs of other similar tools). It soon becomes evident that this utility was designed to be as configurable as possible and not the most visually attractive piece of software.

Basic yet very intuitive and well thought-out user interface

As mentioned above, the utility's tabbed interface is quite straightforward with an intuitive layout, a small menu bar on the upper part of the main window and two tabs right underneath it, one for the Lists Editor and the other for the Main Settings section.
Basically, Keppy's Synthesizer allows you to import and edit lists, as well as import specific presets from SF2 files. It also provides you with a quick way to switch between eight saved lists.

The highlight of this utility is clearly the provided level of configuration

Furthermore, by taking a look at the File menu, you can open a built-in, self-explanatory mixer and a blacklist manager. It is worth mentioning that the app also enables you to assign a soundfont list to specific sound utilities, as well as to set the synthesizer as the default MIDI output device.
It goes without saying that the app also provides you with an impressive set of audio and driver configuration settings, most of them readily available from the second tab, while others from the Additional settings drop-down menu.

Simple and efficient MIDI driver

All in all,  if you are looking for a performance-orientated and highly configurable MIDI driver and looks are not your top priority, then Keep's Synthesizer is well worth your while.