OP

Quoted from PinWoofer:

PinWoofer is pleased to introduce our new Knockout Amplifier (aka the "KO") . The KO has been released to Spike and JJP platforms and is now available at PinWoofer.com.
The KO is a smaller format compared to our GT amplifier and removes some of the features that are not highly useful in the modern Spike and JJP platforms. Specifically, the KO removes a few features in the pre-amplifier stage that includes auto-muting, GT electronics, studio level line-out and the differential input with gain control. These features remain highly useful for earlier platforms so the KO will not be made available for WPC, WPC95, Data East, Sega / Sega Whitestar, Stern Whitestar and SAM. These earlier platforms will continue to be serviced by the GT amplifier. Please note that the KO has the same final amplifier stages compared to the GT and has the same output power capabilities. Choose your amplifier option at check-out.
If your goal is to dramatically improve the sound field of your title, the KO will provide an amazing audio upgrade. For most of PinWoofer's customers our internal / self contained solution is more than adequate to meet needs so the KO solution will provide what you'll need to get a great result with little effort!
On a final note there were two goals for the KO. The first was to simplify the system and offer an amplifier more appropriate to the modern platforms mentioned above. The second was to reduce the cost and pass this savings along to our customers. The former was achieved. The latter was partially achieved; due to an unprecedented and constrained supply chain and unexpected increases in our cost of goods sold, we have increased the base price of the GT. Fortunately the cost of the KO, while not reduced to the level we had initially hoped, is currently $45 less than the GT. So, if you have recently ordered a GT kit your purchase price was similar to that of the KO.
Thank you for your support!