I'm currently using a Rotel RB-951 power amp to run some vintage 3.8D Fuseliers. They are pretty beefy and require a 4 ohm load, with a range of 50-125 watts as far as I can tell (information is slim on these online).
However, with my Eskinsin bluetooth adaptor plugged directly into the amp, or using a Kenwood Kr3130's tuner plugged into the amp, I am only able to get up to a maximum of 70 decibels with the meter in between the speakers. The clipping indicator on the amp does not come on at any point.
Since I seem to have such a distinct cutoff in volume, regardless of the input method, I'm thinking that I must be reaching the power limit of my amplifier. Does that sound right?
The Rotel does not offer power specifications on 4 ohm loads (but it can do them, per the manual). At 8 ohms it's rated at 50w/ch continuous and 100 watts in bridged mono.