Hi Paul,
Alan has a good point, though obviously your setup could be different to ours. He uses the inbuilt intercom in his Trig radio, whereas I use the same Trig radio, but with a Flycom intercom. I take it you have checked that PAW
is saving your volume settings?
The amp you have linked to is a 5 Watt Power Amp - which will be far too powerful for what you need and could potentially damage your mixer.
Personally, if you definitely need a built in amp, I’d give the Velleman kit a try.
Re Soldering... The main mistake people make when soldering electronics is to use far too powerful a soldering iron then compound this by putting far too much solder into the joint(s).
Most ‘Electronics Geeks’ will use a temperature controlled soldering iron or soldering station, but for ‘occasional’ (electronics) use, I get by perfectly happily with a small iron with a fine tip (such as this Antex 15 Watt one).
https://www.amazon.co.uk/Antex-K782470-Soldering-Kit-Yellow/dp/B00D6F3C2YNot trying to teach you how to suck eggs, but I was always taught to keep checking the tip of the iron as it heats up, then clean the tip by wiping it gently on a piece of wet sponge (as supplied in the Antex stand). Next ‘tin’ the tip by applying a
very small amount of solder to the tip and re-wiping it on the sponge before applying the point to the joint for just long enough to heat both the component ‘leg’ and the board so that a very small amount of the solder is drawn in when you briefly touch the end of the solder to the joint. If this doesn’t happen, remove the solder and the iron and try again. Don’t be tempted just to keep the iron in place and force extra solder into the joint. Also leave the joint to cool naturally - if you blow on it or otherwise to try to artificially cool the joint you are likely to end up with a ‘dry joint’ due to oxidation of the hot solder. If the iron gets too hot, just turn it off for a few minutes and let it cool down, before switching it back on and proceeding to the next joint.
That has served me well for at least 50 years, though I did treat myself to a new 15 Watt Antex iron recently.
Best Regards
Peter