The problem is that I'm getting inductive kick whenever the contacts close to switch off the input. This can be seen in the scope image below and is audible as a "pop" at the output.
I have the high pass on the secondary and impedances right where I want them, with a corner frequency at 99.6kHz and slight underdamped peak at about 56kHz. That gives a relatively flat response up through 20kHz. Part of the issue is also that the input should be able to handle 3Vrms, and the spikes are not that high (generally 2-4V). I've read that a snubber circuit is commonly used for this, but not sure where to start. If treated as a low pass filter, the large 220uF cap as part of the snubber would need a tiny resistor to pass audio frequencies, and I think would throw off the impedances.
Would appreciate any useful input.
UPDATE: So after considering the responses and researching mute circuits, I realize the above circuit drawing demonstrates what I wanted to accomplish but is horrible in implementation. Even with make-before-break contacts, trying to break both sides simultaneously and have them do so at the same time to prevent inductive kick is wishful thinking, so I've implemented the following circuit:
While a little slow to charge initially, this eliminates pop from DC on on, and inductive kick from off.
Question: Is it an issue if blocking caps are left floating as opposed to discharged when disconnected? In this case, removing a connection at the input doesn't allow the 220uF cap to discharge.
ANOTHER UPDATE: So an upgrade with make-before-break contacts seems to not have solved the issue after all ... the DC seems to be taken care of, but now I have a huge "ON" spike, and I don't understand where it is coming from. Here is the new circuit:
Here is the result at circuit output (beyond transformer secondary) whenever the relay gets switched:
There is a shorting of the transformer primary for a double-digit microsecond duration when switching on, but this wouldn't be the cause, would it? Also there is a much smaller spike when switching "off". Maybe bouncing contacts? Any ideas?