Incorporating Sub into two channel stereo

i can't believe they would not put you a sub out on that equipment, but krell is not about sub woofers, with the 804s i don't know why, but we all have out listening needs and sometimes want to explore, as i have many times, so in saying that , use the record out and use a bw sub to try and match crossover...if your speaker goes down to 40 , then put the crossover on the sub at 40...hope this helps...record out should give you an output to the amplified subwoofer