JLM AUDIO

Hi thanks I found a few.
I was also curious if there is an easy spot to steal 24v to power a couple more relays. I was thinking I'd just tap off of the relay +. I'm using it to mute the cue signal when the tb is activated.

Couple questions:
1) any recommendations for a substitute for the ever hard to find 2n5457?
2) how can I have an adjustable threshold control? Coarse adjustment would be fine.
3) for an external gain control, would I need a reverse log 10k pot?

thanks