I recently purchased another Muffsy Relay Input Selector kit on Tindie as I'm building another stereo amplifier. The Muffsy kit by Skrodahl is great as it provides 4 relays and a mute function and additionally has remote control functionality that is highly configurable...perfect for my projects. Since my first purchase a few years ago, the IRremote code applications have been developed under Arduino IDE as expected. I had some difficulty in navigating these changes, and contacted Skrodahl directly for help. I'm really pleased to say his support of his products was highly responsive, and solved all my issues.....He continued to follow up through to completion I'm really impressed not only with the quality of this Muffsy Relay Kit but also the great product support after purchase. Highly recommended to all considering a high end amplifier build with great features!!! Eric

Ordered the kit and received it within reasonable time considering the current shipping conditions worldwide (from Sweden to California USA). Kit contains exactly what you see on the website. Assembly was very easy and the instructions provided on the website is so easy to follow.
Programming the ESP32, by following the steps as described on the instructions, is straightforward. For testing, extra resistors were provided for the LED input indicators but you have to supply the LEDS.
I encountered a minor hiccup. Testing the selector with the remote (included) works perfectly. On, Off, Mute, channel steps (sequence: FWD 1,2,3,4,1... BW 4,3,2,1,4..). But manual operation by adjusting the encoder seems to have a reverse sequence than that of the remote control steps. CW starting from Input 1, it steps to 4, 3, 2, then 1. CCW starting from 1 steps to 2, 3, then 4. I sent an email and Mr. Skrodahl responded immediately. No only that the response was quick, but how to fix the issue was described in detail that any beginner will understand. And most importantly, the solution works. Apparently, I learned from Mr. Skrodahl that "there are two versions of the exact rotational encoder board, and they send opposite signals when turned. To make everything a bit more troublesome, there's nothing identifying either board".
Operating the Input selector is easy. Power is supplied by an IRM -02-5 supply. PCB for mounting the IRM-02-5 is included in the kit when it arrived. The selector works as expected. The only feature that I have not tried is the SSR relay trigger. Everything else woks fine and I did not notice any degradation in sound. In fact, I think it is a big improvement compared to the traditional selector switch that I am using, not to mention it cleans up the wiring layout inside the preamp.
I am very happy with the purchase and will recommend it to my friends.
Abe R.

When planning my preamplifier project I searched for a nice input selector and found the Muffsy Relay Input Selector. It meets all my requirements: four inputs, mute, standby function with SSR and controllable with a remote or a rotary encoder. And the Arduino code can be modified, which made it possible for me to add support for a motorised ALPS volume potentionmeter. Build instructions are excellent and it was very easy to build!