I bought this Lead Foot ABY to switch between - and mix together - the left and the right channel on my 22500 Loper's stereo output.
To test channel interference, I used the A and B 1/4" jacks as inputs in which I sent a 0 dB (1 kHz) signal. I connected one of the parallel 1/4" jacks as output to a HI-Z input on an Audio Interface to measure signal strength. There was no change in the signal on the selected channel, but there was a crosstalk of -28dB from the non-selected channel. When A and B input were linked together, the sum of the signals was +6dB.
The buttons are fitted with just 4 cm distance between them which means that you need to be a bit accurate not to press the wrong button by misstake. The advantage is that you can easily press both buttons at the same time if you need to.
When both A and B are active at the same time, both LEDs are illuminated. Therefore - if you forgot the previous A/B setting, you can not determine which of the A and B jacks that becomes active when the Y-connection is disabled. (This could have been encoded with the use of multicolor LEDs.) The LEDs are small and sits deep in the panel and is therefore a little difficult to read in bright light and/or at a large viewing angle, but mostly this is no problem.
There was no problem to get the 9V battery in and out of the box. The LEDs are activated whenever a plug is inserted in one of the "parallel" in/out jacks.
The Lead Foot ABY switch pedal does what it is meant to do. Feels robust, and has a good price