Do you mean a slight increase in noise. I think that doesn't matter here. I recently hand-soldered about 30 through-hole opto couplers, no problem. Failure depends on your soldering skills, and is not likely to happen if you keep soldering time at ~3seconds. You should of course use a temp controlled iron, and know about ESD.
Leo..
Hi Leo,
thanks, than it should not be a problem.
I'm soldering since 17 years and never killed a component with the iron 
I just had some wired NOS audio transistors for a guitar effect, where the seller pointed out several times to never solder them and also in the diy-pedal forum many people told that there is a 50/50 chance to kill them if you solder them.
There were also reports about complete dead ones...
Felix
Doesn't a destroyed component add to the creative distortion most guitar players are looking for? 
Tom.... 
Well some of them believe in that😂
But when there is no signal comming trough anymore, well then you build a "God thanks, nobody needs to listen to that guy" pedal😂
Could be that they were JFET transistors, needed for the high impedance of a guitar pickup. You can indeed kill them with a soldering iron, but not because of the heat. They are destroyed with the slightest static discharge. A common trick when I used them half a century ago was to wrap the legs with a thin copper strand. Then solder, before pulling the wire out. And yes, I killed a few before someone told me that trick.
Leo..
Hey Leo,
yes I think it was about JFET and Germanium ones.
Good hint with the wire.
Regards,
Felix