vsthost 1.56 was available to download from the developer's website when we last checked. We cannot confirm if there is a free download of this software available. The default filename for the program's installer is vsthost.exe. We recommend checking the downloaded files with any free antivirus. The program lies within Multimedia Tools, more precisely Music Production. The most popular version of the program 1.5. This free tool was originally designed by hermannseib.
From the developer:
A program created to understand the inner workings of VST plugins. It's a VST-compatible host that's capable of: loading VST effects, parameterizing / editing them, sound output for VSTis, MIDI-input and -output, loading / saving .fxb / .fxp files, I/O through either Windows MME or ASIO drivers.
You may want to check out more software, such as Blue Cat's Stereo Chorus - VST, Tab Tools or DSP/FX Virtual Pack, which might be related to vsthost.