2 Advent 300 receivers used as mono blocks

I have a question. I have 2 Advent 300 receivers from around 1977. I have never heard of anyone doing this before but just for grims I hooked up my Conrad Johnson PV 12AL preamp to the pair of Advents 300's using just the power section from the Advents. The Advents are rated at 15 watts per channel and I am almost certain that there are NOT separate power supplies for each channel. My question is since I am using 2 Advent 300's one for each speaker in my system am I basically using mono blocks and is the rated power of 15 watts now being doubled(or more) since the entire amp section of each unit is going to just one speaker? I'm surprised just how nice this system sounds after using much more expensive and power amps with the CJ preamp in the past. I have heard of people using double Advent loudspeakers before but never double Advent 300 receivers. Thanks