This device allows the replacement of vacuum tubes with a solid-state device. The user still gets the "tube" sound that has had a resurgence in the last few years.
As a consequence of the replacement, energy used for lighting the filament is saved, and corresponding heat produced is eliminated.
The device is fairly robust, and after being tested in the field for a few years there have been no failures.
The gain in these existing models is the same as a standard 12AX7 tube, which is probably the most-used preamp tube type.
Since it is an engineered device, the characteristics can be tailored to each application.
There is now a high-gain model which has much more gain than any 12AX7.