I have a Supro Blues King 12. I don’t mind the stock speaker. It’s harsh at first, but as it breaks in it really gets pretty cool. I’d like to use the amp a lot for gigging but I’m not sure it has the guts to do some of the stuff I do. The best possibility for making it louder with minimally invasive modding would be a more efficient speaker. But I don’t know what that is. If the stock unit is a 90-94db speaker that’s easy. If it’s already got a 99db speaker I may not be able to get any more out of it. There are no sensitivity specs listed for this speaker anywhere that I can find. The only information I can find is that it’s 8 ohms, 75 watts RMS, and is designed to sound like a 50’s field coil speaker while having modern construction. I don’t want to spend money on a speaker unless I can guarantee it’s gonna be louder.