Can you advise what the distances are to each speaker and what gauge of wire you are using to connect them to the receiver? Too small a gauge will inhibit the signal to the speakers if it's a long run.
For loudness it's more about Sensitivity, combined with the nominal output of the amplifier section of a home theater receiver (we typically abbreviate these as AVR). Think of Sensitivity as how efficient a speaker converts a signal from the AVR into sound. Some speakers are far better at this than others. With better sensitivity less power needed to create the same loudness.
The nominal value is put on speakers in ohms by the OEM. Ohms is the value given to measuring the resistance (impedance) a speaker has to a signal from the AVR - the higher the value the less output from an amplifier. Problems arise when an amplifier if not stable if the nominal value is too low (like 2 Ohms - some AVRs say anything less than 6 Ohms). Until recently most amplifiers gave their output value in watts when connected to 8 & 4 ohm speakers. Now they use 6 ohms and sometimes don't bother to advise the others, which can confuse folks.
You need to all match this for a system to work to it's potential, but you can connect say an 80 watt AVR to a 100 watt speaker and it can work just great. It just won't go as loud as it would with the full 100 watts. But most of the time, especially if you use a Sub, you pull far, far less that 80 watts from the AVR.
The only specs I could find on your yamaha htr 3063 is: 100 Watt - 6 Ohm - at 1 kHz - THD 0.9% - 5 channels (surround). And if this unit is functioning correctly to spec it should have enough power for your new speakers.
