I had 2 15 Daytons in cast frames serII and my nebor complained he could not hear but it vibrated the eath the city said too bad. I think the best sub although I am a Dayton fan for a expensive home system is SEAS L26 ROY (Madison Sound) % used by Martin Logan and others. $100 dollars more for two. I am building a KT120 100Watt amp with NOS ^SL&GT front end and phase splatter and Cyo Harding tubes. Sylvania NOS 1960 Tubes plug them in and immediate difference. Capacitance and regulation cannot be understressed for sub. ( I will use two hafler D200s in meantimeseparted) two B+, Separate filament Xformers Caddock 1 % except .1% in phase splatter and comparator for bias/balance and analog VU with Marchand Bassis for fine tuning. See you at corrected to subsonics bassis is really nice but turn amp . Base is made or break in powersupply storage and regulation. tube regulation from HP lab standard in 1960s audio oscillator is best I hav ever seen. except for tuning cap. regulation was the key to this fine tube lab standard which is a show. . .Gain down low - i smoked a 1970s  EV 15 at 15 hz when Marchand  Bassis was putting out with  125 dBA at 15 HZ (I was saying whow) wires to cone glue caught fire (flames!)  Forgot to turn amp gain down when calc boost at low freq. Zobel network is needed to control peak movement if going below system Fs. I get tight below hearing. It can be expensive but not for ROY. I plugged numbers in with enclosure and small peak can be easily dampened with just LC circuit. wiked one tuned should be tight with no breakup in stero mode triamped or souround sound with DennonAVR##!! two sub outputs. i usally keep one on front speakers electronic tube crossover rooling in at 6 db at 100HZ and boost with Bassis at rooloff.