Did The Trick
I've owned a Fender Pro Jr. for many years, but never used it as a practice amp because it was loud as hell, and if I want to use a loud amp, I have much better amps than the Pro Jr. But sure enough, I swapped in a pair of matched EL844 tubes and now it is a practice amp. The above review from the tube store is dead on accurate. You will loose the clean punch but gain the crispy crunch. Headroom seems to be reduced by more than 25%, so if you are worried about losing volume, stick with the EL84s you have. But now I can dime the amp and it is definitely suitable for bedrooms and preserving the old ears. Add a low gain overdrive or boost or fuzz and it sings for days. I'm satisfied.